Has anyone ever seen one of the D312 truck engines from the early 1940s? They were basically a D4400 with an automotive governor and different exhaust. I've seen the acmoc article on them and old brochures but am wondering if anyone has actually seen or  has one. Thanks, Josh

I think Jeff Moyle has one.

Never seen one before, but wouldn't it be cool to own one along with a 1693 and a 3408? I have truck nut friends that would enjoy having a mix of Caterpillar powered trucks. JM

Are you referring to the D468 automotive engine? Series 1N3001-up.
Edit
After checking my rack setting chart manual I see a D312 Automotive s/n 1N6001-up, based on a D4400
Don't have any info on the D312 and have never seen one.
Looked up the s/n's, started at 1N6001 and ended at 1N6020 so not likely there are any around.
 

The spec sheet.

Then there was the 3412 with a allot more horses! VROOM!

Thanks for posting that spec sheet! I have an extra D4400 I'm thinking of converting into a D312 basically to install in my one 1940s Mack EF. I'd like to keep as close what they were as possible. I believe like govenor was basically that of the D468/D4600 used in the early DW10s so that may be able to be found. The manifolds I'm sure I'll need to fabricate. I believe from my parts book though the intake maybe similar to that of the D4400 marine engines.

If you don't have it already, there are a couple D312 automotive engine parts catalogs on ebay, I could try to cross part numbers to see what applications the parts had, although for some of the low production units and parts, the NPR does not always list.

www.ebay.com/itm/371944218500?hash=item5...tkp%3ABk9SR_7rjM2WYQ