[ArmyRanger]

I'd like to swap a Tremec into my 351w powered '65 Mustang but don't have the $3k+ to drop on a kit right now. I'd like to perform a cost-efficient swap and that's why I'm calling upon the knowledge of this forum.

Were TKO 500 & 600s ever installed stock?

What stock years/models were the 3550 & 3650s instaled in?

Which would be best for my application- a 3550 or 3650? (not talking HP limits, just bellhousing/input shaft length, etc- the mechanics of it bolting & working together)

I already know about the input & output shaft spline differences & etc, that is no bother- I just want a sturdy manual box.

Thanks!

[rj8806]

Originally Posted by ArmyRanger

I'd like to swap a Tremec into my 351w powered '65 Mustang but don't have the $3k+ to drop on a kit right now. I'd like to perform a cost-efficient swap and that's why I'm calling upon the knowledge of this forum.

Were TKO 500 & 600s ever installed stock?

What stock years/models were the 3550 & 3650s instaled in?

Which would be best for my application- a 3550 or 3650? (not talking HP limits, just bellhousing/input shaft length, etc- the mechanics of it bolting & working together)

I already know about the input & output shaft spline differences & etc, that is no bother- I just want a sturdy manual box.

Thanks!

Where to start?

There is no such thing as a budget TKO swap into a classic mustang. It's just not possible (assuming you do it right). The TKO(3550) never came stock in a production car. The 3550 (which is what the TKO is based on) came stock in the trucks of the late '70's and into the '80's (if I'm not mistaken). The TKO, as it is, was never installed in ANY factory production car (unless you consider the 1 time run of the '95 Cobra RR which was not a street legal car, rather a turn key race car made by Ford. It did have the 1st generation TKO in it when it hit the floors.).

The 3650's are a completely different transmission and were only installed in mustangs from 2001 to now, behind the 4.6 modular motor. In other words, it won't bolt up to your 351 block.

Back to the TKO swap into a classic stang. Because of it's size, it will not fit correctly in the tunnel without modifying the tunnel. There are some who have installed it by dropping the tail housing down some instead of modifying the tunnel, but that leads to driveline angle problems (that's a whole nother topic). On the classic stang, there is a stiffener rib running east to west thru the tunnel, affectionately called the torsion bar cross member. Your transmission cross member is bolted to it. In order to get a TKO into the tunnel of one of these cars, that rib needs to be modified. If there was no machine work done to the case of the TKO itself, expect to remove alot of that rib, which will compromise the structural integrity of the uni-body. Some companies offer a modified TKO case that only requires a minimal modification to that rib, which does not compromise the integrity of the cars' body (PM me for more detail or click on my home page in my avatar).


The only other non-expensive option I see for you is a T5. The T5 is a good transmission, it's just not very strong. It's weak link is the 2/3 syncro, so as long as you don't try pushing 450-500ft/lbs thru it, nor slam 2nd to 3rd everytime you drive it, it will last.
The T5 will bolt up to your 351W too. It does use a pull type clutch so you have to stay with a cable operated system but other than that, it is a cheap, affordable option for a 5 speed in the '1964 1/2- 1973 mustang.




Richard
Tech Support
Tremec TKO, T45 & T56 Transmission Systems