4g54 dowel pin centres

the engine in my '88 uses a fair bit of oil and just recently even more coolant. I would like to get a rebuild but I'm not sure what the dowel pin center measurement is for the bell housing. My ram 50 has an automatic transmission. I know that the dowel pin centers changed since the D-50 first came out but not when exactly. Any info would be appreciated. Thanks in advance.

On the 88 Ram 50 2.6, all blocks were the wide bolt pattern, 13.25" on the lower bolts on the bell housing. It changed in 87 for the automatic blocks, as they were 12.5". So , any 2.6 manual block will work from 79 to 89 or auto blocks from 87 to 89.