I got some good info when I posted on my log cars the other day. I'm working on getting my forest products traffic up to speed after ignoring that part of my layout for a while, so here are some wood chip cars. The first is from E&C shops. I don't think anybody else has done this particular car in HO.

The Santa Fe had 35 of these, according to a 1984 ORER. The new date on the data is 1979. I'm not completely sure if cars like this were built so late, but it does seem credible. The Santa Fe ran wood chips in East Texas, Arizona, and on the Sierra Ry in California, mostly in old gons with side extensions. I don't know where these ran, and I haven't been able to find photos on the web. Anyone who knows more, I'd love to hear it.

Next is an SP car from an Ambroid kit that was made about 1970. I assembled it at the time and never got it quite right. I've been doing a rehab -- it especially needs a better wood chip load, the one it has is pretty scruffy. The photo shows it on temporary trucks. This was the first series of modern SP wood chip cars. I don't know if it could run on the Siskiyou line, though.