Internal/External balance?

[lampy]

I already have a thread about my 86 Blazer started, (I'm replacing the motor), I have a question. I have read threads saying if your engine has a one piece rear main seal your engine is internaly balanced, my engine does have the one piece seal. I read the family tree it says 84 is the year they switched to the larger crank and one piece rear main no mention of int or ext balance.87 RWD are hit or miss for int balance, In 88 it says the engines are all internal balance, so is the one piece seal not a dependable sign of an internaly balanced engine? I put the motor back in today, if I have to I can pull it back out to drop the pan and check for the ring in the center of the crank but I would rather not if I dont have to. The fly wheel that was on the motor in the Blazer is for an ext balance motor (big weight cast in the back) that motor also had a one piece rear main, it also had a broken crank (wrong fly wheel?) I'll have to check it to see if it has the ring cast in the center, the pan is still off of that motor. Help!!! I really dont want to pull the motor back out if I dont have to. Thanks!

[geoffinbc]

I replied in your other thread. And no the rear seal is not an indicator of balance only of journal size. My previous post about the seal indicating balance was wrong.

[lampy]

Thanks for helping clear things up! I reread the family tree and it's all there. 84 start of larger cranks and one piece seal,87 are hit and miss as far as balance for the S series engines. I have proof, two 2.8's with one piece rear main seals,one is internal balance the other is external balance.