Anybody know about "welder series?"

I always found those mustang II hot rod kits for the narrow track width to keep the tires inside the fenders never match the factory frame widths of the A-bodies.
Quote from their site "Our 56″ kit likes a frame o.d. of 26″ – 30"

According to this thread , a body is 32-34" OD
http://www.forabodiesonly.com/mopar/showthread.php?t=221060