For crawling i would lock both diffs. Just super glue the spur gear. and give it extra time to dry.
for the lug nuts: maybe because you drilled the hole. With my super swamper i used metal nut. They work fine. You could also use rs's 2-56 hex nuts.
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Track car v2.0
fieldfairy2's mini late model
Operation black widow
H-Crawler
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