307 to 455 swap

[1986cutlass455]

Hi im new to doing rebuilds i know the common sense things but when it gets to technical things i dont know were to start so any help is great. so..... i purchased a 1972 olds 455 and am going to drop it into my 86 cutlass supreme which curently has the 307 my main concerns is what i can do to avoid having to get driveshaft cut and keep everything as easy as possible. I also purchased a G Body Ford 9 Inch Full Floater Rear End. It has full floating axles, Ace Hubs with 5/8" wheel studs, Summit Racing Detroit Locker, 31 spline axles, Motive Gear 4.11:1 ring and pinion, 11.75" rotors with GM calipers... Now i have to purchase the trans im going to get a th400 so the question is what tail shaft should i get 4" 9" etc, to keep same drive shaft length, that is if its possible. so the funds arent the issue its doing it the most simple way.

id greatly appreciate any help

thanks, zac

Also im going to buy headers i know hooker headers are pretty much the only ones to fit easily but do i need tolook for headers for a 86 cutlass or a 72 cutlass????

 

[RockSS]

I believe the short shaft 400 is the same length as the 2004r however I also believe cause of the beefier rear axle you still need to shorten the drive shaft ... sorry for the bad news (lookm at my pic's theres an 84 culass, w/400 thats how i know)

 

[1986cutlass455]

thank you very much for the help that was great help...... also your cutlass is sweet some time ill have mine very similar i plan on doing a cowl inducted hood and keeping vinyl top,,,,,

thanks, zac

 

[joe_padavano]

I believe the short shaft 400 is the same length as the 2004r however I also believe cause of the beefier rear axle you still need to shorten the drive shaft ... sorry for the bad news (lookm at my pic's theres an 84 culass, w/400 thats how i know)

Nope. The crossmember is in the same location as the TH400, but the 200-4R is the same length as a short-tail TH350. The TH400 is still longer, even with the short tailhousing. Also, the TH400 uses a larger front driveshaft yoke than the other GM transmissions.

 

[Blake442]

Sorry, but shortening your driveshaft is unavoidable.
It only costs like $75-$100 to have it cut and re-balanced.

If you were just going from a 200-4R to a short-tail TH-400, you'd still need to shorten it by 1/2"-3/4".
With the addition of the 9" rear-end, you'll need to shorten it even more.