Okay, still confused if I am over complicating this. So in 86 there was a switch from GM from a 2 piece rear main seal to a 1 piece rear main seal.

Does this mean that if I want to do an engine swap on my 85, I have to use a block with a 2 piece rear mail seal?

If the 1 piece RMS block has the flywheel will it not just bolt up to my Borg Warner T5? Assuming the starters and teeth on the flywheels are the same? Or did that change too?

Most of the crate engines out there are 1 piece RMS engines so looking for some help on this.

Thanks in advance.

 

You just need to a flywheel to match the crank and everything else works the same.

 

So the flywheel diameters are standard for small blocks, just the number of teeth to match the starter?

 

It's the bolt pattern and the pilot hole for the flywheel