Do a search for companies that sell fittings and pipe. Victaulic has
blocks that are based on their piping products. I think that Viking
had some as well. I do fire protection systems and there are a lot of
vendors that provide these blocks.
McMaster-Carr's online catalog has links to (excessively) detailed drawings of
their pipe fittings. The specific drawings I have tried, of 1-1/2" pipe tees
and bushings, do not carry gage lines to indicate how the fittings mate with
each other, and the simplified thread representations do not bear an obvious
relationship to the threads on the delivered product.
Which is a wordy way of saying that the drawings of the fittings themselves are
okay, but to make an accurate assembly drawing, you will have to buy the actual
fittings and measure how they fit.