Tim,
The page you linked to is well done.
Here are the numbers for the supposedly 1953 Powerglide engine'
The gray area for 1953, 235, pattern 1, is the block that Jim has. But Jim has the pattern 2 head.
1953 pattern 1 head, low pressure, 3701877.
1953 pattern 2 heads, full pressure, 3836848 & 3835913.
1953 Powerglides all with Hyd. Cam and 2 water pump holes had pattern 2 heads.
The full pressure block castings are:
3701481
3733949
3843363
and were the first with the new 848 and 913 heads and new crank 3701488.
