[Ant]

I gather from reading the posts on CC that G-force GF-5R is maybe a bit stronger, in HD Drag racing than a Jerico RR5, and both of these boxes are rated at around 1300bhp!

Jerico seem to be much much more commonly used in all forms of racing especially Drag racing and road racing.
I have read the GF-5R isnt the smoothest shifting for a race trans, and the Jerico is butter smooth. The five speed Jerico is rated higher than a Jerico four speed!

I guess one bonus is even I could easily replace gears and dog rings in either a GF-5R or RR5 trans, as they appear to be much easier than a Toploader to work on!