It seems my 3 speed only shifts once and you can barely hear it. From a dead stop, I have to creep the truck slowly to hear the shift. What can I do to check it? How do you adjust the 3rd gear (can you?) Am I losing top end speed?

Yes, you can check it.

There are 2 shifting units inside your trans. Each also has an adjuster screw.

Its normal for the truck to shift really fast out of first gear and into second. Then you should hear it go into third.

if your running the X chassis, then just remove the top of the trans case and remove your gears. find the 2 shifting units and make sure they are in working condition. Then turn the adjustment screw on the 3rd gear (smaller of the gears on the shaft.) i would go ahead and loosen it about 1/8 turn. (check your manual tho, i belive it says something about how much to adjust it for each change) then put it all back together. Now that you know the units are good. You can use the holes on the side of the trans case to make your adjustments, again, read your manual.
Hope that helps

It can be hard to hear the shifts over the engine noise. I'm so used to mine that I barely hear it. Anyways, a too rich tune will not allow the engine to hit third. Adjust the carb HSN before adjusting the trans. If you must adjust the trans, the 2-3 shift can be adjusted without pulling the trans apart. Just turn the adjuster clockwise for a later shift and counter clockwise for a earlier shift. [8D]

Unfortunately I have the regular chassis, does it have to completely come off? Either way, once I have the new engine I ordered up and running, I'll check to see if it shifts. Is there a diagram online somewhere that shows how to work on the tranny? Not sure if I still have the instructions.

Just pop off the little rubber plug on the side of the trans and turn the gears until you see a little allen screw line up in the hole. You adjust that little allen.[8D]

Does that one adjust 2 to 3?

Yes. The internal adjustment, where you'd have to go into the trans, does the 1-2 shift.[8D]