On steep downhill descents I have occasionally heard a grinding. I couldn't tell if it was throw out bearing, powerlok clutch chatter etc. My T18 shifter has always been sloppy. The trans itself was rebuilt. After pulling the top and draining the oil it's evident the idler has been sliding forward and chattering on the 1st/ reverse slider. Rebuilding the shifter, new stick on order from Novak. Mines an early (76 Wagoneer) doesn't use the nylon fork inserts.