Block to Trans Spacer question
 

I'm going from a c6 auto trans to a zf5. Can I use the same spacer between the block and the trans??

I doubt it; you need that zf5 one I bet I have I will check difference for you and follow up. I bet starter will not work properly

Thanks, that is appreciated. I'm running a 77 engine now, with a efi starter for an auto. I had to add a washer between the starter and mount to get it to disengage and not engage when I punched the gas. I will check the opening before I put the trans in, but if it is only thickness that is a concern, then I will go ahead with the install of the zf. Oops, I just thought about the pilot shaft. Well, I'm going to find out how it works. Everything is scheduled and has to go today. Hope it works. It is another of the small details that no one mentions when doing this swap. Dagnabit.

Count the teeth on the fly wheel/flex plate I believe with most autos you have the smaller one and need to switch but the c6 and zf5 are the bigger pattern

If I need a larger opening to allow for the flywheel, then I'll modify the plate. I was concerned about the thickness of the spacer plate and it would affect the pilot shaft depth into the bearing, and also how deep the starter teeth engage the flywheel. I don't believe the older spacer is thicker than the newer one specific to the zf. If there is a thickness diff., it is minimal. Hopefully it won't hurt the p.shaft bearing, and I will be able to add a spacer between the starter and trans to keep the starter from engaging too deeply.

When you mate a 77 engine with a 91 trans, there are many measurements, etc., that no one knows, and this, the thickness of one spacer as opposed to the other, and how it affects the p.shaft/bearing interaction, is one of them. Thanks for the help.