First, in checking the wishbone, is it the type with the rubber ball, which has a cast iron lower cap that is tightened against the upper cap, or is it the Ford type, which should have 2 springs held in place with cotter pins? The latter type is better if its in good condition. The rubber ball type works ok when the ball is new, but the oil that (intentionally) drips from the transmission to lubricate the ball rots the rubber, then the steering gets really bad. I far prefer the original Ford design. On the original type radius ball, there should be about 1/8th inch space between the top cup and the lower cup. If not, the cups and/or ball are worn. The nuts are tightened against the spacer ( found within the spring) and then backed off one castle and cottered in place. If thats all good, look at the spring shackles, perches or kingpins for looseness. Check your pittman arm to ensure it is tight against the sector shaft. Check the steering box to ensure it is tight against the frame. Check wheel toe in, to see if its not toed out. Check wheel bearings..they should only be ever so slightly more loose than tight. In most cases with steering trouble, it is a combination of several small faults in the steering system that add up to a big one.