I have 1960 lark that is sitting on a 91 chevy S-10 frame and my 4x4 is not engaging. I change the switch on the transfer case and the actuator and still no 4hi or low.The cable is not broken or stuck and I could not find a vacuum leak. When I put it in neutral the right side rear wheel spins as it is still engaged in drive while the left rear does. Any advice would be great. thanks

 

Couple of questions to clear things up:

- Do yo know which model S10 it sits on? Automatic transmission or manual?

- Are we talking a manual 4WD changer or an electric one with a lighted switch with two lights? (green/amber)

- You state: "I change the switch on the transfer case" What exactly did you do?

- When you troubleshoot and say: "When I put it in neutral" The transfer case or the transmission?

- Again for that troubleshooting. You say the "right side rear wheel spins ... while the left rear does." Does what?

The 4x4 on the S10's is normally out of the transmission into an NV2xx transfer case. Depending if it is an electrical or manual transfer case you switch it "manually" or with an electric motor which actuates the same shaft as the manual lever would on the transfer case.
The transfer case always routes the rpm of the transmission through to the rear axle. (2 HI)
It has a chain drive which can be actuated which will drive the front axle through the output shaft forwards. (4 HI)
It also has a reduction which can be switched after the 4x4 has engaged and reduces the shaft rpm of the input shaft roughly by 2 (halves it) which gives a lot of torque at lower rpm. (4 HI)

This is roughly how that works.

 

https://blazerforum.com/forum/tech-a...ill-help-7180/

 

I will try to clear things up a bit. It is an automatic and manual shift on the floor and when it is in 2wd and neutral the right wheel spins as if it is engaged, the left wheel does not spin. The transfer case switch had oil in it so I replaced it when I pulled the transfer case to replace the shaft seals. As of right now the front wheels do not engage in 4wd and none of the lights work on the floor shift. Thanks

 

If I got that right:

- Engine - Automatic Transmission - Manual Transfer Case.

- You had the transfer case out of the car for a seal replacement?

I would suggest to use the information in the aforementioned links and check all the linkage to the transfer case.

Not sure about the manual TC as I have never seen one in operation but it should have some electrical connectors as well to give position, depending on the year the chassis is from.