have a 74 B210, A13 engine, with the 3spd auto behind it. I'm looking into "upgrading" to the 4spd if it'll fit and such as the extra gear would be nice for the highway driving that i do on a regular basis, and help a bit with fuel mileage! (dunno what it is there but it's currently $1.30can/L on average so more than the states and their bitching more than us! bloody americans! (no offence to forum members from there lol just a harmless jab, hell my g/f and her parents are all american citizens!)

Anyways, to my point, I was wondering about the bell housing and length specifically.

I have found that the come in a few model of nissans up here that i can find in the wreckers (and rebuild for cheap, joys of being an apprentice mechanic in a transmission shop) unfortunately since their behind L series engines, i'm unsure of their usability.

Would it be easier to do an L series swap or what?

Also found the 3 and 4 spd have all the same gear ratios for the 3 gears with the 4th gear being a 0.6something ratio (3rd is 1.00) so i know after conversing with the other guys at my shop that it won't fall flat on it's face or be sluggish with the 4spd

well the bell housing are removeable so perhaps you can fit an A-series bell to the L-series transmission.

But I think no one has done it yet. Details are on Datsun1200.com: L4N71B Swap

dd, i was looking at that wiki page actually but the only thing i really saw helpfull was this...

"L3N71A/L3N71B converter housing for A-series engine

* Will this fit on the L4N71B? "

Quite possibly a trip the the wreckers is in order since it's getting nice out now, and see about finding both of the transmissions if i can, take the bell's off and see if it'll fit on the other.

Or tomorrow at work, call one of our parts suppliers and talk to them!

From memory I think that they will interchange. the L4N71B is longer [not by much] and thats about it.