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hey gang,
I have a 64 1/2 mustang that has a 260 v8, had automatic transmission.
I'm upgrading to a late 90's 5.0 and a T5 5 speed manual. My question comes to the rear differential gear ratio. I'm thinking about putting newer model rear axle in it with disc brakes and 8.8 diff. Anyone have my engine/trans combo? What gear ratio are you running? This car will be a cruiser, not a drag car. It will run 75 on the interstate, etc. 3.55LS a good choice? 3.73? I'd appreciate a little input. I'm going to research what are in newer mustangs and see what ratio fits the masses.
PleasePlease,really talk to lots of people onconcors side..If you actually have a early 65, then it is worth Double to Triple price than a late 65 car... If it has not been cut all up in pieces..End of the day it is your car, drum brakes are the best on rear end.. 8in has all you need..If truly 260engine,worth more than 289..I have had and do have late 65's and 66's.. Would love to have an early 65 car.. everyone will tell you lots of things to do to it, I just advise talking to Mustang people.. I know you want reliable car....Put the petronic(sp) point replacement, and newer carb on a 302 and then drive it.. Main thing is drive it, you may find out it is alot of fun driving..
 

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When you say 5.0 are you talking about a Coyote or a 302? Big difference. My '69 convertible came with a 302, a C4 and 2.79 gears. I swapped in a set of 8" 3.55s that was given to me by a fellow Mustanger. They've been in the car for a lotta years now and I even drove it across country in 2009 with those gears, but, with a 3 speed automatic, the car runs at some very high RPMs on the highway and is a major gas hog. My son has a '69 SportsRoof with a 351W, an FMX and 9" 3.25 TracLoc rear end. The car was originally a 2.69 peg leg. He had converted it to 3.73s but the car was almost undriveable with those gears behind the 3 speed FMX. Highway RPMs were over 4K. Both cars have had a couple of cam changes as well.

I agree with the poster above. Seems a shame to modify an early '65 if the car is in decent shape. Maybe you could find a later '65 to mod up and keep this one as a concours restoration.
 

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Discussion Starter · #23 ·
no I'm not talking about the coyote 5.0. A late model 302, late 90s roller engine.
It is an early car, I think right around the first 9,000 made.
Here's the deal with the 260. I have nothing against it, and I would use it, but a 5 speed won't fit it. Its not keeping the automatic, that's just not even a consideration.
This car isn't going to be a collector car. This car is being built for my wife. Shes wanted one since we were 19. I'm 48 now. She's waited long enough. I was lucky to find this car and I am building it to suit her, and our needs. Its not going to be sold until we are dead so I really don't care about its value.
Its going to be a nice clean well built car. AC will be added. I bought a complete AC system from a 65 mustang, not sure how much of it we will use, but at least the inside parts. She wants this car to look mostly original and drive and handle like a much newer car. So that's my goal. It will be painted the original Caspian blue, interior will be black, it was blue and white originally. Someone changed most of it to black years ago. We will make it new in black.
I'm going to research this 8" diff. I may just keep it and build it to suit. As far as the width of an 8.8, I though maybe a ranger rear would be close? I could get wheels appropriately back spaced if its not too much. I don't want to need crown vic wheels on it. The deeper dish looks good. Maybe the stock 8" with a new set of leaf springs and quality shocks is the way to go. I'm going to check it out. Front end will be rebuilt basically stock, it was recommended to upgrade to better bushings which I will do. And I'm adding a power steering box. I was going to do a mustang II front end but I've read that these handle pretty good in stock form so I will go with it. If we don't like it we can change it another time after getting some time on the road with it.
I'm not a purist, but I keep Ford parts in stuff I build. You won't see me drop an LS in it. It may not be all original, but it WILL be Ford!
Thanks for all the info and advice!! I appreciate it
 

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no I'm not talking about the coyote 5.0. A late model 302, late 90s roller engine.
late 90s roller engine.

Meaning 5.0 HO OHV Engine? Beginning in 1996, the 5.0 roller engines were gone, replaced by 4.6 OHC.
 

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The Explorer 5.0 is a great choice! But there are a couple of considerations. Be sure you get headers that fit the GT40P heads specifically (although I think some '98s got the standard GT40 3-bar heads instead of the 40P 4-bar heads) P heads are the best factory casting ever put on a Windsor (not counting the Clevor "Boss 302" here), but that's not really saying too much. The springs on both heads are very weak, because all Explorers and Mountaineers had really wimpy truck cams with low lift that make all their torque at low RPMs and poop out at low RPMs too. Replace those with a good set of springs and something like a 5.0 HO cam for an 85-1993 Mustang (or any mild aftermarket grind) and you'll have a really efficient little engine with great power. If you go aftermarket, something like a Comp Cams 258 or 264HR would be about right. I would avoid going with higher lift and overlap, because it will start to impact low-rpm manners and mileage.

You'll want to use a front sump pan. The one off your 260, and oil pickup might work. You may want to get a different timing cover that has a provision for a dipstick, as the one on the Explorer has it mounted on the side where the shock tower will make it un-fun to use. If you do replace the timing cover, then you'll have to replace the water pump, damper, and all the pulleys and brackets too, so that'll be a small pain.

Your 260 intake will have tiny ports and is ill-suited to performance. Consider an Edelbrock Performer 289, as it would be well-suited to street use, with good economy, snappy throttle response, and crisp performance. It should also fit under your hood!

If it's in the budget, a Holley Sniper EFI system will let you run fuel with alcohol content, and not worry about rebuilding your carb every year. If you decide to go old school, check out the Summit M-series 600 CFM carbs - they're a descendant of the old Autolite 4100, and work great - so long as you run alcohol-free gas.
 

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Sorry for jumping back in late, but are you certain you can’t fit the T5 onto a 260? I know the alignment pins are different at the bell, but I could swear I remember either a mod or a bell that could fit this setup.. have you talked to the guys at Modern Driveline? That’s where I’ve gotten all my swap advice and parts and they know their stuff. I am also one against the molesting of rare or unique Mustangs, but if it’s just swaps etc that can be easily undone and for driveability I’m not too offended. Either way it’s your (or your wife’s) car so you do you! I’d keep that 260 wrapped up in the garage for value later tho..

On the 8.8 swap.. having done it I will say it was not really worth the effort. If it’s just for fun and a cheap Frankenstein swap I support it, mine was just on a 66 inline coupe I built from a POS to a little street rod with a V8. I had to swap the 7” rear and it was junk. But the 8.8 I took was from an exploder, gave me the LSD and gearing, but stuck the rear wheels out a little further on each side.. you could cut down the housing and axles if you really wanted to prevent that, but it suited me fine I just had to roll the fenders to keep the tires from rubbing. They still rubbed a little with my 2 buddies in the back seat. The biggest snafu we hit was setting the pinion angle incorrectly when welding the spring perches back on the housing, we thought we had it right but were off by a hair and the car would vibrate violently when backing up. I didn’t bother fixing it.

If all that’s worth it to you and you can avoid my mistakes I’m sure it could be a rewarding experience. If I had the choice again and was trying to have a “nice” build as you’ve said, I’d spend the money on gutting an original 8” and building it.. you can do all sorts of cool stuff like beef up axles, add the locker/ LSD, etc, there are many companies who will supply parts or build them for you (Yukon, Currie). Of course the gold standard to me would be to just drop in a new built Currie 9”.. they have them in their catalog built specifically for first-gen with everything aligned and set, they build it for you when you order.. at a cost of about 5k. That’s what I’ve done on my January-built 65 fastback build with a coyote swap.. see the purists can yell at me too! But it was a C code so they can’t string me up 😂
 
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