Big Block originality Question

[Winnone]

Hi everyone,

I'm contemplating buying a second '72 Cheyenne. The potential new one is a Super Cheyenne and in really rough shape.

Based on the VIN it is a half-ton. The engine is a newer SBC (HEI, and newer style brackets etc.). I crawled under and took a picture of the tranny - it looks like a th400.

If the tranny is original, does this mean this is an original big block truck? Was there an option package that put a th400 behind a small block?

There isn't an option sheet in the glove box. Any other way to find the options for this truck? Any other way to figure if this was originally a big block?

Thanks,
Frank

[Howitzer]

Check out the exhaust hangars on the rear frame next to where the exhaust exits. They should be riveted to the frame, one on each side as big blocks were true duals i believe.

[71swb4x4]

I am pretty sure th400's came behind small blocks too. The build sheet can answer all your questions if you can find it. Usually they are behind the seat springs but have also been found under the carpet and even on the back of the cab between the bed and the cab.

[leddzepp]

If it's an original 72 big block it will have a high hump tunnel (bolts in) and a heat shield on the bottom of the cab, real close to the passenger side exhaust manifold.

[72chevyk10]

i thought the turbo 400 trucks all had the high hump anyway?

[68350]

The heat shield on firewall is big block only. Exhaust hangers. Should have the th400 switch on gas pedal if its originally a th400 truck. Should have 400 engine emblems.

[71 super]

The big block swb should have a bolt in tunnel, the heat shield and dual exhaust brackets. It is very possible to have a th400 and low hump small block truck, look at 68 model trucks, mine included trans options were manual or two autos- power glide or 400, both with low hump. Some early bb trucks (lwb) were also low hump trucks. The heat shield should always be present on any 71-72 bb truck as well as the dual hangers as bb were only trucks to get dual exhaust from factory. Also the gvw plate on the drivers b pillar should be at 5300 or 5500 rather than the 4800 or 5000 gvw of small block trucks. Long and short trans was optional and could be had in any truck so th400 does not mean you had original bb just bigger trans. Remember everything was an option and these trucks were built according to the person ordering, be it new buyer or dealer.

[RenoKeene]

One other thing that has not been mentioned, factory big blocks had a remote power steering reservoir mounted on the driver's fender.
Almost forgot the 4 row radiator....