I need help Identifying these parts. They say D6 tack rig and they are solid brass. Anyone have any ideas? Thanks

these parts should be transmission fork

gemdozer is correct - they are transmission shifter forks. It's entirely possible a previous owner has scrawled "D6 tack rig" on them, to ID the parts to a particular machine he owned, that was identified by him, as the "tack rig". The description is not a Caterpillar parts description, they are known as a "yoke" in Cat parts terminology.

If you look closely, there should be a part number stamped on them, comprised of, a number, a letter, then four numbers.
Most Cat parts (about 95%) have the part number stamped or cast on them, the remainder usually have a P/N tag, either cardboard or aluminum.

If it has had a tag from the factory, and it has been lost, you are stuck for precise ID, unless someone recognizes it accurately. The fact that it has "D6" on it, is a good pointer, however, D6's have been built in probably at least 50 different models from late 1937. From 1935 to 1937, they were known as the RD6.

Check for a casting number. The only time the casting number matches the part number is if there are no other operations done to the part.

If anyone was wondering what a tack rig is, it is a crawler with welders and other tools attached that works along with sidebooms on pipeline projects.

Very often a D6.

CS

If you wanna see more google it...

With casting numbers the dealer has an NPR book, but probably is on computer now but the casting number will be changed to the new assembly number in the files if as OM said there is other work done to the casting (part).

Thank you for all the responses. I've looked these over exstensively and haven't found a part number. I posted the forks on here in the hopes someone would recognize them. I've taken them to the local transmission shop but he wasn't to excited about them. Just wanted to try here first before they get put in the next scrap load.
CarlSharp, thanks for posting the pictures. That makes sense since these parts came from an old pipeline company.

Don't throw them out yet.....in looking closer they don't have the right shape for transmission shifter forks....and I don't believe the transmission forks are brass (got one laid out I can check).
I'm thinking those are PTO shifter forks which would make them sort of rare and right on a pipeline D6. If they are PTO shift forks the part number would be 8B1782. I can't remember if they are brass or not but I do recall them failing occasionally if not detented properly.

Well, that didn't pan out....forks are missing from one spare trans and I don't want to open up the other. Maybe someones got one tore down but I'm sure they are steel plus the trans forks have remote detent hold where the ones in question show the boss for the self contained detent ball and spring.

I believe these are the PTO clutch forks. They were common on D5 & D6 tack rigs. If they are for sale let me know.

Jeff @ 585-721-7929