[Fot] GL-4

[Randall]

>  but, on the other hand, Redline's tranny lube is GL-5 

Not according to their web site :
http://www.redlineoil.com/products_gearlubricants.asp?categoryID=7
(or what's printed on the bottles I have)

Their "gear oils" are rated GL-5, but generally not recommended for use in
synchromesh transmissions, because they are too slippery for good synchro
operation.  

But even so, they don't have the corrosive additive found in conventional
GL-5, so should be safe for use in Triumph differentials.

Randall