5 speed manual fluid type and how much?

[1977_chevyman]

I have a 1990 c1500 350 and 5 speed. I just installed a new motor and when I installed the trans it leaked out some fluid. Here is the problem I have no idea wich one I have tranny wise. I went to autozone and they have 3 or 4 different trannys for that year of truck. I would like to change the fluid but I dont know what kind or how much.

If it helps any it has an external slave cylender and there is no removable bell housing. It's one piece.

 

[94Sierra4x4]

Chances are it is either an HM290 or 5LM60 (5-speeds prior to the NV3500)
They take I believe 2.2 Quarts of GM Synchromesh.

What I did was remove the fill plug from the transmission and pour the synchromesh fluid in from the shift tower. (Shifter was removed from transmission)
Pour fluid until it drains out the fill plug. When it stops draining, replace fill plug and your good to go

 

[1977_chevyman]

ok whats the difference between the 2? like is one better than the other?