Yes Howard the OB tank is over 6 1/2 deep at the front where the DT tank is only 4 1/2 ins. My friend Doug Mclachlan at launceston is in the process of having a DT tank made but if there is a chance there you would need to provide all the soldered fittings.
regards Alan
PS OH NO I meant Bob My old friend Doug has long gone from the scene passing the DT to Bob