Postby datzenmike » 22 Dec 2017 19:07
You have a '77 620 so get a 71B 5 speed for it. It is absolutely DROP IN. No need to change anything but put the speedometer pinion from your 4 speed in it to keep the speedometer accurate. Even the shifter is the same and in the same location. The dogleg is too short so you will need to modify the transmission mount and lengthen the driveshaft. The speedometer pinion won't swap and you have that irritating reverse above first shift pattern. For a truck you need the faster 1st 2nd rather than the 4th to 5th shift. Nissan saw fit to use a six cylinder 4 and 5 speed transmission in the later heavier and larger engine 620 for a reason. They are stronger.
Doglegs were only used in the '77-'79 S10 200sx and rarely as an option in the A10. They are rare and very likely well used by now. They are adequate for a light 510. The FS5W71B 5 and the F4W71B 4 speeds were built for use in the 280z and 810, both were heavier six cylinder cars and co-opted for use in the 620 truck. The biggest advantage is they are more plentiful.
'77-'78 280z
'79-'83 280zx (non turbo) I don't advise the '80-'83 transmissions as the OD it too high, but you can.
'78-'80 810
'81-'84 Maxima
'78-'79 620
'80 720 (2wd)
That's a lot of transmissions to pick through and these are only the L series ones that directly bolt up!
If you swap your 4 speed front case on you can also convert the following transmissions to L series..
'80-'83 S110 200sx Z series
'84-'86.5 S12 200sx CA series
'82-'86.5 720 Z or SD series (gas or diesel engines)
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs