Cars were nitrocellulose lacquer starting in 1925. Trucks were enamel at least through 1932. As long as the lacquer paint has not bubbled, crazed or pealing it can be scuffed and top coated with most modern systems. It is best to test a small inconspicuous area first to verify there is not an incompatibility with a solvent or thinner. If there is any doubt best to go to bare metal. 

@chip Thanks Chip

Hello Lou,

For your second question about the instrument cluster - only one of the three gauges are the same from '28 to '29. That would be the Amp meter, and Oil pressure gauge. The other two are close but not direct replacements. The speedometer will have a different ratio and actually mounts slightly differently on the instrument cluster insert. The light switch for the '28 is also the light switch for the '29 but the switch itself is different, and they added an electric heat gauge for 1929, so it also is not the same. The key activated electrolock mounts in the instrument cluster insert for the '29, but is next to the steering column for the '28, including the trucks. One of the easiest ways to tell a '29 instrument cluster insert from the '28 instrument cluster insert is the hole for the 1929 electrolock will be about 1" in diameter and the same hole for the 1928 cluster is only about 1/2" for the choke cable.

Clear as mud, right? Hope this helps. If you have any other questions contact the forum.

Art 

@arthur-p-sell 

Yep, that is very helpful. It is the amp/oil pressure gauge that I need, so that gives me a larger pool of salvage from which to search! LOL

Thanks Art