I'm going to be taking the 400 out of my 75 Crew Cab Hi Boy and replacing it with the 466 out of my 77 Hi Boy. The Crew Cab is a manual while the 77 is an auto. I've never done this swap before, but I think at one time I had read that when bolting a 460 to a 351/400 manual bellhousing, the bellhousing needed to be spaced back a little further to make room for the 460 flywheel or the clutch fork?? Also, I will need to put a manual flywheel on the 460 and an auto flywheel on the 400. Will I need to have the engines re-balanced to do this?? The 460 is older (pre 78) if that helps anything. Any other issues that I may need to address while doing this swap??

 

You will not need to ballance either engine. You will need a neutral ballanced flywheel for the 460 as the pre 78's were internally ballanced. You will just need to buy a flex plate for the 400. Im not sure about the back spacing the bellhousing. Ive read some guys have to and others say they havent.

 

Any idea if a 184 tooth flywheel from a 390 is neutral balanced?? Would the manual flywheel from the 400 be an option?? How many teeth is the 400 flywheel?? Worked on both FE's and 385's but never a 400.

 

Im not positive. You could post those questions in the 385 section of this forum and get fixed up. I recently did this swap but I have a C6. good luck

 

I've heard of guys using a spacer but I think their problem was the transmission main shaft bottoming out. If you put your pilot bushing in the outer step ( furthest rear ) in the crank your tranny's main shaft will bottom out. If you install the pilot bushing in the inner most step no spacer will be needed. Anyway that's what I learned the hard way !!! Also I went out and counted the teeth on my 400 flywheel and it had 180 teeth. I was told the 400 is balanced differently than the 460 so I couldn't use that flywheel. I had no other issues tranny related when removing my 400 and installing my 460 with a NP435 tranny.

 

A 400 flywheel will NOT work on a 460. A 390 flywheel will however.