Never thought I would see a time you need to fire up a chainsaw before driving your truck!
These are my best "guesses", Fatman. Probably right but there are always exceptions.
I agree, one of the 400 series, 450.. 470, who knows. Short frame, likely a 3 ton.
Engine would be a 270 or a 302 cubic inch. I would bet a 302.
Clutch plate is 9.5 inch (10 inch - 10 spline). Trans will be a Clark 5 speed or a Spicer 5 speed. I will go with a Clark. You will love a Clark crazy shift pattern. 10 inch band brake on the backside of the trans. Your bellhousing trans bolt pattern will be typical Chevy / GM just as small trucks of the era. An SM420 four speed would bolt right in. If a Clark, maybe a 202V, but more likely a 205V or early 250V trans. 250V would be better, parts are still available. Clark of this vintage will be tagged driver's side, middle, near top edge.
Rearend will be a two speed, 8 point something low, 6 point something high. Appears to be cable operated. Your rearend will need no repair if water has not got in. The axle would have to be completely submerged for water to enter. Those last forever. Parts periodically appear on Ebay.
Vacuum fitting on your firewall, driver's side up high, indicates your brakes have a "hydrovac" unit, in essence, power brakes. Large unit, hard to see, under and between frame behind the cab, passenger side. Lack of a vacuum unit for shifting the rearend in the same location as your vacuum fittings suggests a cable operated rearend shifter.
Only took me two years to find a rebuild kit for a hydrovac. However, those units never go bad. Probably still works just fine.
A hydrovac indicates you will have twin wheel cylinders, two per wheel, 1.5 inch diameter. Shoes will around 4 inch by 14 inch each. No replacements around but easy to send in for relining. Brakes, when in good repair, awesome. Light touch on the pedal, great stopping power.
You have a hydraulic lift bed. Parts not too difficult to find. John Deere or Caterpillar parts will work if you can figure out right part numbers.
Rims, hard to see. Might be 19.5 inch or 20 inch. I would expect split rims if 20 inch. Your rims will be a Budd or Divco style, no modern replacements of the same size. Your rims are "hub centered" rather than "lug bolt" centered. Tires for both size rims are readily available, like Denman and others. You will know more once your truck is up out of the mud and cleaned off.
Only serious problem I see in your photos is no air cleaner. Odds are good water has entered, if not directly through condensation. If water has made its way through open intake valves, cylinder walls will be badly damaged. Might have to bore all the way to eighty-thousands, maximum limit pushing it. You can sleeve the cylinders or simply find another block which is less expensive. I would not attempt to turn over this engine. Head removal and inspection is called for.
Other problem is no gas tank cap. Trash can the gas tank, don't even think about using the tank. Replacements are cheap.
Do you have a good running chainsaw? Have fun!
Billyray
