Actually I just did an oil change on my '48 (with a 55 261) and it had a NAPA 1006 (Fram C4) in it and I changed it to a NAPA 1100 (FRAM C21P) and either way I had approx a quarter inch clearance all the way around the filter.

Remember.... even though the inside diameter and height may be correct, the smaller the outside diameter the less filtration you'll have. Regardless of what filter you use, you should have approx a 1/4 in clearance around the filter for flow.

If the 1100 NAPA filter fits in all ways except for the outside dimention..... post me the inside diameter of your can, and I'll look up the correct filter in my WIX/FRAM books diametricly and see if I can find a filter that will work for your specific application.
Michael

\'48 chev 2-ton boom truck (Boomer)
'49 Chev 2-ton flat bed
'65 Chev 35ft school bus
'88 GMC 6500
'72 Superior 26ft class "A" coach
'50 Farmall "M"
'71 MGB GT
'68 Austin-Healey Sprite
'65 Austin-Healey Sprite
and various other odd British cars
and lots of old radios.....

Although we know what the speed of light is..... What I want to know is... How fast is the speed of DARK??