Put a (shift) fork in it, its done... 98 GMC Sonoma

[riccnick]

So I've been going through the 4x4 system on my 98 GMC Sonoma in order to get it back to operating condition. It was working fine for a while, then a melted vacuum line caused me to replace the vacuum switch at the t-case and run a new line away from the exhaust. Worked fine after that, but it kept clunking in and out at the front diff. Replaced the vacuum actuator underneath the battery, hoping this would solve the issue, it did not. So I jerry-rigged the cable in the pulled position so that the axle would be fully engaged all the time. This did not work either. So I climb under the truck to see whats going on on the differential side of the equation. Pull off the cover for the cable, disconnect the cable, and look at the shift fork shaft (the part you can see sticking out of the diff). Pull on that as if i were pulling on the cable, and it slides in and out fine. Put some tension on it as I rotate the front driveshaft, and I can feel the shaft moving in and out as the ring gear rotates. I'm assuming the shift fork is shot? Or is there a little pin that got sheared off at some point? Anyone been inside this front diff? Estimates on how hard it would be to replace the shift fork and related hardware, or how much a shop would charge? Any info much appreciated. Thx,

[riccnick]

Nobody? No one's been inside this diff?