Someone postulated earlier that the curved steering arm being out of shape might cause a symptom like yours. Here’s a few pics against a tape measure if you’d like to compare.
I have trouble believing this is your problem, but doesn’t hurt to look. I've broke two steering arms on my '57 GMC (one while turning left at a dead stop, the other while trying to turn left at a dead stop with the right wheel & tire up against a curb), but I don't remember ever seeing one that bent. Both showed signs of a developing crack.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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