How To Identify A Rb25 Or Rb20 Gearbox?

[kresot9]

Hey all

I am going to check out a r32 with a rb25det conversion and the owner is not sure what gearbox is currently in it as the conversion was done by the previous owner. How can myself when i go check the car out see underneath if its an rb25 or a rb20 gearbox?

Thanks

[iruvyouskyrine]

If it looks big it's 25. If it looks small it's 20.

RP71C is cast into RB20 box as well I believe.

It's best to just look at some pics online and get an idea of what each looks like before going to have a look.

[jiffo]

20 box is skinnier behind the bell housing and has a more ribbing.

Really, they don't look too similar at all.

[kresot9]

ohhkay sweet, thanks for the info guys