Which one - or other, would you say is better?

 

Having to choose from your two options, I think I'd go RP.
Otherwise, I like GM fluids, and Lucas Fluids as well.

 

For my stock rear end and gears I just use the recommended GM 80-90 and the GM limited slip additive.

 

Generic dino juice with additive is cheap and works fine.

Rich

 

Y'know, the more I search around and read - the more it seems that people think it's better to break in the gears with dino and then switch to synthetic after 500 miles or so.....

There is too much info available sometimes on the interent - it's difficult to sort through it all and find the best thing to do.

 

I use amsoil in everything these days. Before that, I used redline in the tranny and rear.