@etn, if I would be in your shoes I would just accept the airplane as it is and forget about the autopilot
If for whatever reason the AP is something you absolutely must have, then I would suggest you convert the aircraft into a taildragger, there are freely available plans or rather blueprints which would guide you along the way. The conversion would transition the aircraft into homebuilt certification regime and consequently allow you to install whatever avionics, electronic ignition or gizmos come to your mind 
But then homebuilts cannot fly IFR without getting special authorisation and AFAICT that is difficult.
As I wrote on another thread Badin Crouzet is now part Thales Aviation which still makes custom autopilots to order. As well as for CATs it makes mini autopilots for drones and 4 axis for helicopters plus a/ps for the military.
These include all instrument approaches up to Cat 3 if I remember correctly.
I have not investigated costs or whether they still repair Badin Crouzet or whether it would be possible to equip a DR 253 with one of their autopilots.
They do say they deal with legacy autopilots.
Daher have repair shops which deal with most Badin Crouzet instruments, altimeters, ASIs etc (a legacy of Rallyes I assume) but I haven’t yet come across one for the autopilots.
There are several avionics facilities other than Daher in France but I have never asked them of they could repair or modify a Badin Crouzet
Finally there is an STC for fitting the Stec 55 and 55x to the Robin DR400 series the same one might also allow it on the DR 300 series. I don’t think the DR 200 series is included.
gallois wrote:
Finally there is an STC for fitting the Stec 55 and 55x to the Robin DR400
are you sure there is an EASA STC? or FAA STC?
Looking at the failure history of Robin STCs (see below) it is doubtful that anyone did an STC for an autopilot which is a relatively much bigger job than anything that goes into the panel.
Also the installation would exceed the value of the plane. It may be of value to the individual customer but the overall demand would be low, so the chances of an STC being developed are low.
I am pretty sure that comes from the EASA STC list If I get a chance I will double check.
There are autopilots in many Robins (usually the larger engined variety) especially tje DR480 or 400/180.
reading my mind Peter 
gallois wrote:
I am pretty sure that comes from the EASA STC list If I get a chance I will double check.
I take your word for it
gallois wrote:
I am pretty sure that comes from the EASA STC list If I get a chance I will double check.
There are no EASA STCs for autopilots in the DR-400. The STec 55/55X installations are done under a TC holder’s major change.
Apologies @wigglyamp I obviously can’t tell the difference when somebody tells me "its possible to fit an STEC 55 and 55x in a Robin 400.
I also freely admit that it was one of those off topic answers you get when you start asking questions about Badin Crouzet and A/Ps for a DR253.
Also this is not a 400.
With Robins, it always comes back to the same debate. Avionics range from hard to very hard. It was built as a French aeroclub plane, for that mission profile. Various avionics people tried and then walked away. Aspen for example offered to do an STC, publicised the opportunity via avionics installers, but dropped it like a hot potato and denied having done it, when they realised nobody would actually extract their wallet from their pocket.
Socata would have been the same but did a lot better because TBs get used much more for touring than Robins (as a % of the airframe community of about 2k in both cases) and thus owners are much more willing to spend money. On Robins almost nobody wants to spend money, so those that do end up in a dead end.
