[Tigers] gear oil

[coopdvm]

Being as anal-retentive as I am, I noticed the link provided earlier to the
Redline oils GL-5 product says great for Toploaders, but does NOT specifically
state that it is protective of the brass syncros like their GL-4 product
states. I assume the Toploader has brass in the syncros, no? A couple of
questions:
1. My toploader upshifts perfectly, but downshifting not so well. I suspect
the syncros are worn, but if I wanted to try a different fluid, which of these
Redline products would be best for balky syncros?  (Currently running GL-4
product from NAPA)
2. The product you guys recommend for the tranny okay for the diff as well?
 
Thanks!
Bill