Clutch slipping/not grabing in 3rd and 4th gear.

[jasondart]

First post, I will introduce myself a little later, but had a question. I just picked up a:

1968/1967 pickup
1 ton
manual
345
4x4
vin: 783208h766468

when going down the highway/city the clutch does not seem to grab when in 3 or 4th gear. I mean it shifts nice, but if I give it gas, the engine revs, but I do not get a transfer to wheels unless I slowly increase rpms.

Engines, I am good with, but transmission....

 

[Bitterwinds]

I'd check my adjustment. If that doesn't help I would get ready to replace the clutch disc.