To model a 25 with the later bodyshell there are a few options. In the olden days of the 1980s and 90s A1 models used to make a kit which included etched bodysides and cantrails and you had to modify the front of the loco yourself. Also in the 1990s Silver Fox produced a resin body which I’m certain is just a Hornby/A1 conversion cast in resin. In more modern times Bachmann have produced a 25/3 but the cabs are the wrong shape so probably the only option for a good model is to use modified Hornby cabs (just file off the nose and open up the centre window) or Silver Fox cabs on the Bachmann centre section.
I wasn’t looking to build another 25 but having taken a Bachmann and a Silver Fox body to Scaleforum this year to show the differences to anyone who was interested (not many were) I found myself getting itchy fingers and, without stopping to think it through properly, a razor saw soon had the cabs cut off both bodies and a big file made short work of truing them up so I could araldite the SF cabs onto the Bachmann body. At this point I looked at the fronts of the cabs and convinced myself the Bachmann one looked better so out with the razor saw and araldite again and soon the Silver Fox cabs had Bachmann fronts. By cutting just above the handrail I was able to dodge having to make a new ‘rail from brass wire and hide the join unobtrusively. The cab sides now needed extending down by 1mm to match the fronts but as I’d done this anyway on 25029 I didn’t feel the need to worry.
Below is a photo of a Silver Fox cab, a Bachmann cab and the Silver Fox cab with the Bachmann front inserted.