on the lift cylinder part...
i think the more prudent question would be more presicely does the cylinder have telescoping pistons? One inside another and when you raise it is there one coming out of the bottom of the shell too?

Or...
is it just a single cylinder in the middle with a ram coming out of the top and 2 more smaller diameter cylinders on either side of the mast? (not the tilt cylinders) these would be long cylinders mounted on the right and left side of the mast channels.

judging from the model numbers its a gamble guessing which ones are on there but i'm banking on it being a telescoping cylinder. Those are a royal pain to reseal, if you have leaks at the top the other seals wont be far behind. Your best bet is to remove the cylinder assembly and take it to a cylinder repair shop if this is the case. I've done one and its no fun... let me tell you ;o)

as far as the clutch as you call it, the left pedal correct?
take a look behind the steering column under the dash and see if the brake master cylinder is tucked under there? also look for a 2nd cylinder mounted right beside it? Does it resemble anything like this? 'Then check the fluid in the resivoir and see if its low. The resivoir on these units was mounted under the dash area i believe.

If not mounted there then they would probably be mounted on the left and right side of the truck just under the inner floor plate area inside the fender area. I've seen them in both places...
being you have 2 different models like this you may have both scenarios between the 2 trucks. On the outer mounted resivoirs they would be part of the master cylinder assy.

on the spool valve? there is no adjustment except for a possible rod adjustment to center a lever travel, a rod with adjustable yokes on it. Other than that the spools themselves are not adjustable, only springs and a detent that keeps it in center.
if you have drifting tilt then there is a high possibility you have packing in a cylinder bad allowing it to bypass and drift forward. It could be either side since the hydraulic circuit is counterbalanced between the two. You will have to isolate each one and test it for bypassing to find the bad one.

Sounds like you got your hands full here... good luck and happy fixing! :o)