I was a young Inf LT with 9ID during the "High Technology Testbed Divison" days of the late 80s. A BUNCH of FAVs running around in the division when it was transitioning to Motorized MTOE. The Fast Attack Bns (2-1 and 2-2Inf as I recall) had a horde of the rigs. Mix of Mk19, M2 or TOW mounted. The CAB-L and CAB-H had them in Bn Scout Platoons.
FAVs had all the nifty bells/whistles but just totally unsuited to Big Green. Too "high strung". The Scout Platoons of the Mtx Bn had something like 8x FAVs in 1985-88 period. When we deployed to Yakima Firing Center for a typical 20+ day FTX the went thru an average of 2-3 engines per FAV over the course of the FTX. Cost a FORTUNE buying/rebuilding the things. Loaded for exercise it was as if took an Indy car (a real one from back when) and strapped a 500lb steamer trunk on each side. They just couldn't handle the loads. I always wondered whe BS the Seals were doing to keep some of the things operational. Perhaps they just abandoned when they broke.
I was the BN S-3Air for quite a while on a couple big airmovements with C-130, C-141, etc. LONG LONG ago but as I recall, scale weight (no crew) for aircraft load plan of our FAVs was over 4200lb. WAY to much stuff. But they were neat.