Nissan L6 sumps are not interchangeable with RB sumps. If they were, all the people fitting RBs into older Nissan & Datsun models would save themselves a lot of time and money....
Be careful when you're searching for data on Nissan L-gata engines, as there were a lot of different versions made over a long period. Don't confuse the 4cylinders with the 6 cylinders ( 'L20' could mean both, and when the original L20 six - designed back in 1964/5 - was updated in the late Sixties and the 2 litre four was introduced, Nissan called them the L20A and L20B respectively ) and remember that both rear-sump and front-sump versions were made in the L20/L20A/L24/L26/L28 & their diesel variants. There were also some winged 'low profile' sumps in some models.
L-gata sixes were the inspiration for the new RB-series when it was being designed in the mid Eighties in that Shinichiro Sakurai and his team were building a new modular engine series that could be adapted with many variants, but about the only thing they share is their head bolt pattern.
