I bought two NOS Autolite heaters, just the cast parts shown, cheap at a tractor show this past weekend. I gave one to my friend that recently gave me the cylinder head I needed for or '28 Sport Coupe.
I just installed the exact same heater on mine this passed Saturday. A few minutes with the grinder, shaved off a couple spots . . . and it lined right up.
I'll take it off in the spring.
Updated. Added pic. Finally found a good use for that wire.
Around here $20 to $40 EACH. I passed on one which was $15 and willing to dicker, but the connection end had a crack out of it and why bother when another $10 would buy me the undamaged part.
The manifolds to fit these run $20 to $40 too - but be careful since there are a couple of *similar* manifolds which have the bolts in slightly different spots and don't fit.
The fellow I bought from had one on his '29 pickup with a stock manifold. he made two "J" hooks from threaded rod to hook around the manifold and extend up through the holes in the heater and fastened with washers and nuts on top.