Top: Date: 1957, Owned by Jim Priebe
Bottom: Date: 1950, Owned by Mike Cizek
The 72H was produced from 1955 to at least 1968. I suspect it was discontinued in 1968 with the arrival of the 60H, 62H, 71H and 73H bass trombones. It has a #5 Bore (0.562"). I have read that the bore of the Conn bass trombone valve section is (supposed to be) 0.594".
Since the 72H didn't start production until 1955, the bottom picture is impossible, right? The serial number dates it to 1950. In 1950, Conn was still producing the 70H, which is essentially the same as the 72H except it is tuning in slide. The trombone in the bottom picture is stamped "70H", but it has tuning in the bell and not in the slide. Which would make it a 72H. Perhaps a pre-production model? You do see those from time to time. Or, perhaps it was a special order by someone, in which case this instrument may have given Conn the idea of the 72H. Who knows. Either way, the owner knows the two previous owners, and is quite sure it is all original.
I read on the OTJ Forum that "The lead pipe on all 72H's were set up to take a Remington shank mouthpiece, which is a different taper and overall length, than the standard large shank Bach mouthpiece. You will need to have Remington shanked mouthpieces, to properly fit the lead pipe."
What Conn said in 1959:
A new model extra-large-bore bass trombone in Bb and F with pull to flat E. Features tuning slide in bell section, Crysteel Airfloat slides complete with slide barrel springs for first position adjustment, outside slides of special Conn bearing formula alloy. Length 46½", weight 4 lbs. 9 oz., bell diameter 9½".
What Conn said in 1959:
This large bore horn is the bass trombone standard of the world! Big tone plus smooth response. Extra slide length and spring barrel for accurate tuning gives flexibility. Extra rotor slide length allow flat E tuning when needed. Fast, dependable Airfloat Crysteel slide. Features: 9 1/2" bell, springs in cork barrel for accurate tuning, tapered rotor guarantees perfect port fit, blanced Crysteel slide action. Lustre-Conn finish.
What Conn said in 1966:
The top bass trombone among professionals. Widely used in symphony orchestras, concert and studio bands. Resonant dark sound. F rotor with E pull plus full 7th position for complete chromatic range to pedal Bb. Brass bell. Bore size .562", Bell 9 1/2". Length 46".