As to your question about OC-6 front grills, the 66,77,Super 66,Super77 and 660 would all fit for your crawler. The 88 and Super 88 will NOT fit as they are different. The side panels are completely different on wheel tractors and will not fit. As far as were to find these check with Landis Zimmerman out in PA. The grills are being reproduced by Korves in IL.
Hope this info helps! Mike