strange 4wd problem

[Detroit Dan]

Last snowstorm I used 4 low a few times, which I normally do in a few places due to big hills and so forth. Anyway, what started happening is I would have 4 low engaged and working fine, when I shifted to reverse I didn't have front axle engagement anymore. After about 10 seconds you would feel it engage, but of course I had to be careful not to be spinning at all when it happened or it would bang when it did engage. How the heck can this be? It felt just like when you shift it initially into 4wd high if you don't wait the few seconds for it to engage. But it was already fully engaged and working going forward, so how could it disengage or whatever in reverse? Also, I've always had positive, instant engagement going into 4 low, unlike 4 high which takes a few seconds.
I'm guessing an actuator problem (never replaced it yet) and hoping it's not tranfer case. I have an oddball t-case, a lot harder to find than the ones most of these trucks came with.

 

[trouttrooper]

x2 on actuator. If it's getting weak and not completely engaging then it may slip out when changing direction. Of course checking wires is always good too

Generally as long as you don't get grinding noises or can't get the low range then the t-case is fine.

I believe '97 didn't have the thermal activated actuator. Those were notorious for failing