Here are some photos of my TIE Crawler tank in progress. The conversion uses the old MPC TIE Interceptor. Based on the old kit, it is approximately 1/48 scale.
I haven’t added the armament yet. I plan to paint the tank whatever gray I happen to have enough of and handy.
I bought the conversion direct from The Fourth Axis (http://www.thefourthaxis.com) back in March. I just checked their site and I see no mention of the conversion, so it may be out of production. I already had an old TIE Interceptor from when they were being clearanced in the late 90s.