Over time I have asked a fair number of questions about covered hoppers in the steam era. The Google photos link shows the results of some work to make the Intermountain 1958 cuft covered hopper more accurate based on the Railway Prototype Cyclopedia articles and my October 1954 modeling period. See:
These are factory painted cars with simple mods to make them more representative of the prototype. They all needed new brakewheels and trucks.
DT&I 11841: These came from Intermountain with their version of the type 2 roof. I removed the toe holds and changed the brake wheel to a Kadee Equipco plus adding Tahoe #8 trucks. The reweigh was already correct and some chalk marks were added.
PM 20096: This used a Kadee Ajax brake wheel, Tahoe #13 ASF A-3 trucks, and a Plano US Gypsum running board. Chalk markings and new reweigh/repack decals finished it off.
NKP 99750: This used a Kadee Ajax brake wheel and Tahoe #7 trucks (not 70T, but the spring package looks right to me.) Chalk markings and new reweigh/repack decals finished it off.
SHPX 25581: This used a Kadee Ajax brake wheel and Tahoe #7 trucks. The grab irons were painted black. I swagged at the reweigh/repack being by the Q at KC since it was in their lease and used FCR as the color to paint out the old. There is no definitive answer to this point about when they were returned to SHPX from Q lease.
SHPX 25402: This used a Kadee Ajax brake wheel and Tahoe #7 trucks. The grab irons were painted black. This car started life as SHPX 25592 leased to the Q like SHPX 25581. The 59 and the lease information was scraped off and it was renumbered 25402 and the lettering "LEASED TO HALLIBURTON OIL WELL CEMENTING CO." added to the sides.
RI 332: A Detail Associates Ureco brake wheel was added (not shown - will retake pic later) and Tahoe #13 trucks substituted. I scraped off the original return to lettering and changed it to "WHEN EMPTY RETURN TO OTTAWA, ILL." Nobody had any additional information on RI covered hopper return to lettering, but Ottawa is what I am modeling and they had a very large sand plant that needed many cars to serve it. Ottawa is also shown on cars in later period pictures. Reweigh/repack decals finished it off.