DT or HST does not matter. The power beyond is the same. I bought a BH 77 off craigs list 2 months ago and a friend and I removed the hoe and sub frame from a L3800DT and it is now on a L3700SU. We are average shade tree guys and as far as time a hour we had it all off and the factor power beyond hose, lift arms, fender brace and tool box on the 3800. (We did have air tools) I put it on in close to 2 hours because of torqueing all the bolts. Once it is on you should be able to drop the hoe in under a minute.
Has anyone figured a way to leave the lift arms on? This the only draw back to the Kubota vs the BH7500 Woods I sold. I could swing them in and tie them with together with a rubber strap. Still looking at the 77 as to a way.