1 (F)/AG 123 and AR 234?

[Nick Beale]

You might find this helpful as well. The appendices include very detailed breakdowns of the individual aircraft on strength from the unit's origins through to April 1945.

http://www.ghostbombers.com/recon/234/Goetz/goetz1.html

There was no trainer variant in the Ar 234 B-series (or none that got built and entered service). The night-fighter (sometimes called the B-2/N) had a normal single-seater cockpit with an improvised radar operator's position in the rear fuselage. The four-engined C-series, of which perhaps one or two actually reached a unit, was going to include two-seater cockpits however.