I have tried posting over at a pontiac web-site with no responses. I have always found great answers here among other members, an hey it is an F-body! I have a 78 TA. 400 4spd. It has a rod knock and needs a new crank. In searching for cranks I have heard not all 400 cranks are the same. My year requires a 2 1/2 inch centering ring. The problem is I have heard not all cranks are interchangeable. Some some cranks will not work with a 4spd. Is this true? If so, how do I make sure I get one that will work for me? Freakin' Pontiac, Got to love the interchangeability of the SB/BB chevy!

The centering ring (think its called the flywheel register?) can have different sizes. I believe the later model cranks are smaller.

While its possible to bolt up an earlier, larger center-diameter flywheel to it, not a good idea as you want a snug fit to ensure that its centered.

try eagle rods and cranks. im using one in my 65 gto with a 455

Hi Lindsay, the "register" at the rear of your crank is .250" smaller than the early shafts. I believe in the '75 year they did away with the 2.750" register.

You have one of two options, first, find a late shaft, second, find an early shaft and change the flywheel.

You will most likely be balancing this deal anyway, so to change the wheel is not so bad! Also much easier to find the earlier pieces! (Or you could go new as mentioned, I have used the "Eagle" brand "strokers", but I'm not certain they have a 400" stock stroke available?)

I have about 2 or 3 Pontiac resto's in here at the moment and recently delivered another, all have the pilot bearing provision!

(Caution) DO NOT order a flywheel from "CAT", they sell them for these units, and we recently had an issue with one! Had to return it and get a used OEM!

Thanks, Gary in N.Y.

P.S. Not certain about the later Pontiac cranks, but I do believe they are ALL drilled for the pilot bearings. Oldsmobile (and some very older Chryslers) is "proprietary" with the stick vs. automatic cars and the cranks. Drilled a number of pilot bushing holes in them years ago!

Thanks for the replies! You guys know your stuff! It was the fact that the crank needs to have a pilot bushing hole drilled that I guess I was looking for. I have found one a guy wants $20 bucks for (may need ground?) but it came out of a running motor. Doubt I can go wrong at that price as long as it accepts the pilot bushing.