did some digging on the forums and from what i gathered,
the rb20det comes with both rb71c and rp71c gearboxes,
some people say they have the rp and some have the rb
don't know if one is just newer that the other
got this on one of the forums
'RP71C #2', the ratios are 3.32, 1.9, 1.31, 1.0 and .838.
these ratios matches the nissan factory service manual for the rb20det manual transmission, (the gearbox for the na engines has a different ratios set)
however the manual makes no mention of RP71C or RB71C