I've brought this up on here before, I got a '67 chevy 4x4 short bed with a 4 speed. It will only go maybe 50mph, at first I thought it was stuck in low range but low range is even lower,. Could it be just the transfer case? Some experts say I need to change entire drive train. She's a sweet rig from the Idaho desert , Id hate to replace everything .

3 inch lift with some 33's will give you a bit more on top

Do you know your axle gear ratio ?

Even with 4:11's in back, it should do better than that. Special custom rear end?

I have a '76 chev that has 4.56 gears in it and 50 is all it wants. That puts it at alittle over 2500rpm.

They are telling you right about switching gears. You will also have to change carriers as the carrier for gears below 4.10 are different.

Big tires as mentioned, but you don't gain a whole lot unless ya go really big.

Your transmission and transfer case are fine. You have very low rear end gears, probably 4:88 or lower. The only way to get decent top speed and lower engine RPM is to change the rear end gears to 3:73 with average size tires (about 30” tires) when running that transmission. I had a truck with the same transmission, 4:11 gears, and 30” tires. At 65MPH the engine was screaming. With 35” tires the rpms came down a few hundred when driving 65.

I eventually dropped the manual trans and put an overdrive automatic in the truck. Much more enjoyable to drive as an automatic.

I’m gonna take a guess and say you’ve a 250 in-line or maybe a 292 in-line, my 1968 short bed 4x4 had a 250 in It factory, we changed it out to a 292, and top speed was 65 and that was all it would do, pulling a load of dead fords behind it or not lol. Just please keep in mind those trucks were made to pull, not for speed

I had a 68 Dodge that was owned by the forest service. It was much like yours.

There is one other way to get you some top end speed, but you gotta keep your head together. That is to install an inline overdrive in the rear driveline. It works well, but you have to have it in 1to 1 if you ever shift into 4X4 or engage the transfer. If you screw up, it will bust something, usually the overdrive. It can be kinda a train wreck waiting to happen if you forget, that's what I ment about keeping your head together!

Thanks for the input, yes, its a in line 292 and the guy I got it from said it had a "mini spool in it" so both rear wheels always turn. She's a nice truck but around here everyone drives VERY FAST! Even on dirt roads on paved roads forget it . My '59 Willys does a little better but both are a road hazzard around here.

lol my old 78 chevy was gear bound at about 60 mph.
350 with a 4 speed and 456 gears, got 7 mpg with a stiff tail wind

Bosco- Not trying to hijack your thread. When I first saw this thread, it reminded me of two YouTube songs.

That Old Chevy Truck- https://www.youtube.com/watch?v=fgRf0723FSI
And also
Chevy song- https://www.youtube.com/watch?v=Yc5TcEgjaP8

To be honest its probably like my ford f100 they are just slow I am afraid I'm gonna break something if I go over 60. And its got 3.00 gear and a big block