so on both of my 150's, an 88 an 93, how would i go about fixing my 4 high gear? low works great but thats all i got, i dont have a great idea on what to start with so any ideas guys?

 

Do you have an electric or manual shifter?

 

How are you determining that your 4x4 hi isn't working?
Your front wheels won't drive but they will in 4low?

 

its gear select an in 4 low i can actually watch the front wheels spin, in 4 high they sit there as if its still in 2wd, the 4wd light come on but it seems like nothing changes in the transfer

 

could this be a auto hub issue?

 

For anyone who is trying to diagnose a 4wheel drive problem, it's very simple.

In 2hi with the truck not running get under it and spin the front drive shaft with your hand.
It should spin freely.

Now leave it in 2hi and lock the hubs,
Get back under the truck and spin the drive shaft by hand, if the drive shaft can't spin and you can see your outer axle Ujoints rocking back and forth well your moving the drive shaft then your hubs are working.

Now unlock the hubs and put the transfer case in 4hi and get under the truck and move the drive shaft back and forth by hand.
If it doesn't spin then your transfer case is engaging properly.