[MDeezie66]

I have a 1966 mustang that originally came with a inline 6 engine and guessing the rearend is orignial also, im wondering do i have to swap out the rearend or do any modification to it when i install my new 400HP engine? Can i still use that rearend in the mean time just to cruise around with? Or do i need to beef it up all at the same time with the engine swap. Any advice will help, Thanks

[mustangmadman33]

i would not recomend it but im sure if you were very easy on her that you could temperarily use the rear end the way it is. i would take care of the rear end before or at the same time as the motor tho.

[andrewmp6]

Read this Six Cylinder Upgrade V8 - Mustang & Fords Magazine

[67ragtopStang]

I'd look for a 9" rearend for your car. It's virtually bulletproof and is what I'd get, if I were installing a 400HP engine in my Mustang. I've heard that 8" rearends are good for about 300HP.

[havoc65]

You could run the stock rearend if you took it easy it would probobly be ok but if you were to try and smoke a camaro at a traffic light you may have a problem. A 9" would be the way to go put disc breaks on while your swapping it out.

[slmdlow]

hello all. I am to doing a engine instal but i have run into dificultys with finding a 9" or an 8" so i might have to go aftermarket on that part of the car. I thoght i had gotten one in my other post that i had made, but wen i went to go pick it up it was nether. So good luck with the rear end and yes everyone doce say a 9" is the way to go, as for me my surch for a rear end continues.

[67ragtopStang]

Make sure the rearend will fit your car. '67 and up Mustangs are wider than your '66.