GMC offered an Eaton 22,000 tandem in the 400 Series in the early 50's. It was the tandem that had the interaxle drive shaft going over the front banjo housing. They didn't build them very long because they couldn't match the reliability of the Rockwells that had the throughshaft in the forward axle. This one appears to be a 350 series. However, in 1955 GMC built a 424 for the government. It looked like a 370 series, but It had a 302, twin disc clutch, 5 speed and single axle. I have a parts supplement dated November, 1951 where it lists a HC451, HC 454 and HFX 652. This may have been something specially built for the government. My parts book has no illustrations, so I don't know what they looked like. I really doubt that a drag axle would have been used on a Fire truck. As far as weight goes, we hauled 1,800 gallons of Diesel on a 450 with a single axle.
Here is a picture of the 424 GMC the way I bought it.
https://plus.google.com/10819770718...2841998386&oid=108197707187186692269I removed the expanded metal grill, installed a chrome grill from a 370 and shortened the wheelbase to accept a fire rescue body to make a rolling tool shed out of it.
