1971 GMC Bus - Toro-Flow DH478

[bigblockv6]

There was a military ambulance version of the fishbowl bus that had the twin turbo version of the DH478 designated as the DT478. I also saw a pic of one in a civilian full size fishbowl that may have been for the Australian market

[BobBray]

I volunteer at a rail museum, and we have a '67 TDH3501 that we use for touring people around the grounds. The 3501 is about the last of the 'Old Looks'. The old bus runs very well, I just hope the engine stays together!

[Steve]

Nice! Got a photo? The 3501 was succeeded by the 3502 which was the last of that style. The 3301 New Look replaced the 3502 in 1969.

[BobBray]

Originally Posted by Steve

Nice! Got a photo? The 3501 was succeeded by the 3502 which was the last of that style. The 3301 New Look replaced the 3502 in 1969.

I'll try to get a picture next time I go out. I know there was a 3502 in '68, but I am not sure what the differences were compared to a 3501.

[dsljim]

I've never heard of the turbo version in a bus, at least in a GMC Transit bus.
Mine came from a bus, the story I read was they were put in busses during the Vietnam era, and they were converted to ambulances.

[bigblockv6]

I've got GMC service bulletins from the late 60's to 70's that mention the Turbo version DT478 in the military ambulances.

[BobBray]

The DT478 was used in rear engine GMC school bus chassis (DSPA 5000's?) that were built with Superior bodies for the U.S. Army. The buses could be converted into large ambulances, a common feature of Army buses at the time. As far as I have been able to find out, these buses were the only vehicles built to use the DT478, though there were marine versions of the turbocharged ToroFlow. Many of these buses were eventually re-engined with small Cummins V-8's after 8-10 years of service.

[bigblockv6]

GMC never posted Torque or any horsepower figures for the DT478, it be interesting if those could be found

[BobBray]

Originally Posted by bigblockv6

GMC never posted Torque or any horsepower figures for the DT478, it be interesting if those could be found

Good question. It is as if GMC was testing the DT478 in the Army buses, maybe they were not sure how much boost it could stand. This was all before the ToroFlow II came out, so it was right during the time GMC was having issues with the ToroFlows.

[bigblockv6]

So that was during the era of the D478 ToroFlows rather than the DH478's. When I get a chance I'll check those bulletins. I do remember because od durability issues of the D478's and D637 engines GMC did have a recall campaign where modifications were made to these engines and they repainted from yellow to Alpine Green and re-designated as DH engines