GL5 in sm465 and HO72

[wtb853]

Hello all:

I just nursed home a 2WD 69' C20 fleetside with a 292 and sm465. She is just what I have been looking for. The truck is straight (rockers aren't even -that- bad) and relatively untouched. The first order of business is a tune-up and changing out all fluids.

Most of my time is spent in the Willys realm with flatfender CJs. You are always warned about putting any 80w90 gear oil in the old T90s with any kind of additives, GL4, GL5, etc.....Apparently the additives eat away @ the brass synchros, blocking rings, etc. I don't know much about the SM465 other than its solid reputation.

Is it OK to use modern (GL5) 80w90 gear oil in the SM465 and HO72? What do you all use?

Thanks in advance. Pics soon to follow.