Which is better? Probably a newbie question but want to make sure. I am going forged bottom end 383. Thanks again.

 

If it is going in an LT1 block it needs to be 1 piece.

 

LT1 uses the 1 piece like the above post says. I bought a 2 piece seal rotating assembly and used a seal adapter. Don't do this! If you don't get it properly aligned, the seal will leak and the motor will have to come back out and apart to re-do it. If you do happen to get a 2 piece seal rotating assembly cheap, make sure you get a GM PP or a Moroso adapter.
It will be properly machined and will include the dowel alignment pins. Have someone who has done this before help you. Don't go the EBAY cheap way out.

 

Whew, thanks guys. I don't want to pull that motor out any more than I have to. Can you tell me what to look for or have any pics?

 

the 2pc rear seal is better for hi rpm use its has the larger bolt circle

The seal adapter should not leake if installed properly