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I recently bought a 1970 R700 Dump which my son is using almost daily in a small excavating business. I have a few questions.

Tag on the side says R700. Tag on the door and on the right frame says R685-ST-9964. Is there anyplace that lays out all the model numbers and what they mean?

I've seen references to getting info from the Mack Museum. Is the best thing to do just call them?

I believe it has a 237 with turbo. It has a replacement Eaton? 13 Speed transmission, Camelback suspension. The front drive axle is labeled Mack. The rear looks similar but isn't labeled Mack.

I has an alternater, but it is positive ground. I believe it's pure 12 volt. I haven't seen any indication of a 24/12 relay. I would like to switch it to negative ground to simplify the problems with hooking up a new skid steer trailer. Alternater has two big posts labeled + and -. I would think I could just switch them. Might have to switch some gauge wires. I've worked with old tractors and I don't think switching it would be a big deal, but I'm wondering if there are any gotchas.

Is there anyplace to get some beginning manuals. For example, there is a bit of a leak between the front and main housing of the Mack rear end. It would be nice to have an explosion pic of the rear end.

Thanks in advance.

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Sounds like the frame and hood are from diffrent trucks?? If its a R700 you will have a longer hood than the standard R600 models. If the frame says what you say then i would stick with that serial number as what the truck is. You can contact the mack museum and see if they have the build sheet. send a small donation and you will get lots of info an what the truck was equiped with from the factory. I would guess they just added a long hood at some time for personal prefrence ??? look to see if the cab mounts have been moved that would be a clear giviway as the 700 model cab sits about a foot further back. look at the gear shifters to see where the hole in the floor is for them to come thru. My RS700 has the hole near the firewall where the R600s will have the hole closer in the middle of the floor. if you find a patch or the hole is in the middle this might give you another clue that this truck started out as a R685 with a standard hood.?

Someone could give you more info about your +/- ground issues. I belive you simply reverse the wires on the dash guages, and swith the wires on the batt???but dont quoit me......

look at the pumpkins. most mack rears you pull the diffs upward. other mfg like to place them side ways. the mack side covers may or may not have mack script on them...depending on the year of the truck. the ID plate on a Mack rear will be on the top.passenger side on the slanted plate. it should read something CRD92/93

and below that it will have a ratio..i.e 4.17

hope this helps

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