I found the 3in plug for the bottom of the intake manifold

[refedor]

Carman Faso 716-693-4090 has the 3 In. plugs that rust out in the bottom of some intake Manifolds. Mine was a 1960 LaSabre 364 cu in with 2 barrel carb.:laugh_4:

 

[50sBuicks]

CARS, Inc. also has the plug, 1957 to 1960. 2 Bbl is MP-579 and 4 Bbl is MP-596. Phone is 908 369 3666.