Yeah Joseph is right, Thomas Gast made a video about the 1REC and said they were nicknamed "crabs" in Indochina.
I think it was the M29C Water Weasel, the amphibious version of the M29 Weasel used by US (Army and Marines), Brits and Canadian in WW2.
Crabe was not really an abbreviation, more like a nickname... As mentioned, some light cavalry regiments (like 1er REC) used this equipment in Indochina. As Nick mentioned it's the US vehicle called M29. In Indochina they also used similar (but bigger) amphibious vehicles called Alligators which were US LVT (Landing Vehicles Tracked).
Denims are from de Nîmes (often made from chanvre) and jeans are from Gênes (Italy). The difference was in the way the tissue is weaved (tissé). Tissu/tissue, cloth in English / clout in Scottish (cloutie dumping), gâteau cooked in a clout. my childhood. It's also a praying rag tied to trees, very Celt!
I believe that the de Nimes were sent to US during the gold rush to make tents, awnings and bashes. However before they arrived the role was already taken by canvas (or some other materiel) So stuck with all this extra materiel recently arrived they made clothes out of them. One of the most common being dungarees, The kind of jeans with the stomach protection and braces which we still see today in the farm movies.
Came across this whilst looking up French weapons a Vespa (scooter) 150 TAP "BAZOOKA". Could you imagine what the mods could have done to the rockers in the '60s and 70's ? https://en.wikipedia.org/wiki/Vespa_150_TAP