DeTomaso Mailing List: May 98, Message #229

Never used Hall's cap, pal. It appears to be plastic(?)  The stock pressure
tank has an Italian neck on it that doesn't seal well to slightly shorter US
radiator caps, and is often rough at the sealing surface to boot. I had a
local shop cut the old neck off our tank and solder a US made neck on, to
accept a std. find-'em-anywhere radiator cap. End of problem. Note that if
your cap doesn't seal well, the burped-out water travels down the tank, the
inner fender panel & right into the frame opening, so you may not see such
events by just looking under the car. Meanwhile the frame rails are rusting
merrily away and every 3rd time you run it, the engine gets hot & needs water.
Drill the drain holes, fix the tank neck and you'll not be dependent on a
possibly hard-to-find-except-by-mail part. 
IMHO, J DeRyke