Heat exchangers

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Hello,
does anyone know if 411 or 412 (Type 4) heat exchangers would fit a 73 bus (Type 2), they are both pancake but?

Thanks, A4D

[wgargan]

i think it depends on what year the 411,412 are, i know the exaust ports changed shapes through out the years. some one wlse will have to fill you in.

[Karl]

Yes, 411/412 heater boxes will fit 72-74 buses. But.... 411/412's WITH a BA 4 heater has mini-heater boxes. They only pre-heat the air to go thru the BA 4. They will NOT supply enough heat to warm up a bus.

411/412 without the gas heater uses the same bus box.

Another difference is the EGR flange on the muffler. The 411/412 muffler looks just like a 72-74 bus muffler except they have a flange on the drivers end. The bolt pattern of the bus EGR filter is 32mm. The 411/412 bolt pattern is 30mm.

The exhaust ports were oval with a copper seal ring all the way to the end of 78. 79 change to flat square ports.