my 58 3200 is 1/4, and while it's no longer with me, I'm sure the 57 3100 was the same, I used the same stash of spare parts for both trucks and all the fittings interchange
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics
