T5 Swap Bellhousing Options

Some of the multi-pattern bells don't have all the holes tapped, and as stated, may not be drilled out to tap size. Don't know if there is a specific year range, or if just depended on what trans was being used. I'd suspect that since the standard trans was the T-150 on most cars, the T-150 pattern would be tapped on all and the T-5/SR4 pattern only on those that needed it??Seems like it would have been more efficient to tap them all, but with not many T-5 and SR4 cars maybe not...