4 speed L series trans

[izzo]

over time I have given away all my spare 4 speed transmissions free!.... I am in need of one now... Anyone have one laying around I can get?

[MicroMachinery]

Do you know if a 78 620 one will work?

[izzo]

Do you know if a 78 620 one will work?

I believe so. I can measure this one this coming week and let you know.

[datsunmike]

What's it for??? (car)

[datsunmike]

Found your other post. Yes a 4 or 5 speed from a '74 and up 620 will drop right in.

[wayno]

Found your other post. Yes a 4 or 5 speed from a '74 and up 620 will drop right in.

Tell him about the gearing of them(pre 1980) compared to the 720 transmission gearing(1980+).
This is going into a 720 2wd.

[izzo]

well the long tail dogleg did just fine at 75 and 80 and even 100 down I5.

[wayno]

well the long tail dogleg did just fine at 75 and 80 and even 100 down I5.

The 620 longshaft 5 speeds are different till 1979, some of the 79s came with the 720 gearing, some with the 620 gearing, you have to put it in fifth and turn the input shaft 10 revolutions and count how many times the output shaft turns.
The kid down the road put one in his diesel, the gearing just didn't work, while the 720 gearing works every time.

[datsunmike]

All 620 4 speeds and the '79 5 speed (only year with this) are a wide ratio with a very low 3.592 1st gear. Good for take offs with heavy loads. All will have the same 4th gear so will go the same top speed.
All '77-'78 5 speeds have a 3.321 first gear and are a 'closer' ratio trans.

The '79 5 speed has a 0.882 over drive
The '77-'78 5 speed has a 0.864 overdrive a difference of only 2% which would not be noticeable on the highway. (one MPH different at 50 MPH)

So the 4th and 5th gears are basically the same.

The '80 720 2wd (4 or 5 spd) used the 3.592 1st gear transmission.
The only other 720s to use this gearing were the diesels, the Cab Chassis option and ALL 4x4s.
All other years of 2wd used the 3.321 ratio 1st except those listed above

[izzo]

Did you guys see that information fly over my head? it was a close one! JK! Good info man I get it. I'm not concerned with which trans just yet, more so just getting a 4 speed that will work. and not cause me to be at super high rpms doing I5, but whatever. It will mostly be local runs for now doing 40-55mph. Eagle adam is looking around for a 4 speed for me. I can put a 5 speed in here, someone already put the dogleg in and swapped it for a one piece driveline. SO i think a 5 speed trans would be the right length. Just my wallet won't allow me to get it is all

[datsunmike]

Did you guys see that information fly over my head? it was a close one! JK! Good info man I get it. I'm not concerned with which trans just yet, more so just getting a 4 speed that will work. and not cause me to be at super high rpms doing I5, but whatever. It will mostly be local runs for now doing 40-55mph. Eagle adam is looking around for a 4 speed for me. I can put a 5 speed in here, someone already put the dogleg in and swapped it for a one piece driveline. SO i think a 5 speed trans would be the right length. Just my wallet won't allow me to get it is all

ALL 4 speeds have the same top speed!!! Most 5 speeds too.

All L series 71B 4 and 5 speeds are the same length at 31.5"... it'll fit.

[MicroMachinery]

I have a 620 4spd.