The 19.5 single wheel rims I had on my 62 W300 are solid rims. They are the only size I know of that are solid. Won't work for duallies.
Old chitty 10 lug rims are the same lug circle dia. Therefore, 2 holes matched the W300 and I drilled 4 more to make them fit. I may have torched the center hole a 1/4" or so to get over the hub. That was way over 20 yrs ago. See of u can find a solid rim with that bolt circle. Mine are split rim 20". They used that bolt circle at least up into the 80's and may have had other sizes.

Plastic trucks suck...
Iron trucks rule...