Question on new seals for 7106 FEL

[donrmurray]

I'm installing a seal kit on a 7106 FEL bucket cylinders, and have a question about the internal (rod) seal in the cylinder head/end assembly. This is the seal that the piston rod moves through, so it does have to hold a lot of pressure. The seal that goes on the inside of this assy comes apart. It has a main/larger part and a smaller piece that inserts in a side grove of the main part. Problem is, with the insert inserted the seal is two wide for the inner grove. If I put just the main part of the seal in, it fills the grove. Could this insert only be needed for a different head with a slightly wider grove? To muddy the water a little I looked at the old seal. It's also two part with an insert, but the insert is thiner and both parts together are narrow enough to fit in the grove. Any suggestions on this? Are these two part seals common, and do they always need both parts?