wrote in
Thankfully the alighnment of the gas and water lines was almost
identical but the new heater was about 6 inches higher - had to take
out 6" of vent and shorten both the cold ceed and hot outlet 6 inches
. The gas fitting was 1.5" higher, so I had to replace 2 elbows and
nipples with street elbows - which allowed the gas line to line up
virtually perfectly.
4 hours including emptying the old heater,running out for new 1/2"
unions and ball valve, then the street elbows, hauling the new one
down into the basement and the old one out, and dropping the old one
off at the dump.

Not bad time for all involved. Easier to shorten than lengthen everything.

At work we had an 80 gallon unit leak. It was in there when we bought the
building and the former owner had many more employees than us, thus the
large tank. I opted to replace it with an identical unit to avoid what you
had to do. Everything lined up.