1 or 2 piece rear main seal for 351W

[Black1987Stang]

What's the difference between a 351W block with a 1 piece and 2 piece rear main seal? The journal where the seal rides on the crank and the end main cap?

I'm getting a new one for my 1974 motor, it's new but it sat 8 years and don't want to have any problems so I want to replace it so I don't have any leaks. Summit only has one for the motor

Fel-Pro Performance Z2902 - Fel-Pro Performance Rear Main Bearing Seals - summitracing.com

Should I just get this one or look for a better material?
Anybody know if Advance or autozone has them?
They both have the 9333 PT-1 head gaskets for like $16 each, 10 bucks cheaper than Anywhere else I ever seen so I figured they might have these cheaper.

 

[squeak93]

a 74 will be a 2 piece unless u have had it machined into a one piece. The main diff is that u can't change the 2 piece with the motor in the car, u have to pull the block apart to get to it. One piece is way better, but I ran a 2 piece with no issues.