[sprucegoose]

Thanks for the tips Steve. I just got in from the garage, got it loose by taking a crescent wrench on the linkage rod with the wife moving the lever. It still won't go below 3rd, so I'm running the truck now to warm up the trans to see if that makes a difference.

Yes, I tried to disconnect the cable from the linkage, that was my first thought too. I can't get this rectangular white plastic retainer popped out. First you slide back this black sleeve, and it looks like you should push it out to release the cable end. Don't want to force it and break it. Do you know how this comes off? It looks like it has a little hook in each corner, but compressing those and pushing inwards with a screwdriver didn't seem to budge it.

I don't think it is the Brake/Tranny Shift Interlock. I had that go in my 93 GMC van and it felt/acted quite different. I'll still check it out though.