Fw190A5/U13 was a combo of /U2 and /U8.
This is were you are confused Milo. The FW-190A5/U13 was a long range ground attack varient with the PKS11 autopilot that became the FW-190G3.
The FW-190A5/U8 was the long range ground attack varient that became the FW-190G2. It was not fitted with any autopilot, AFAIK.
Both varients had some of the production run fitted to FW-190A5/U2 nachtjager standards by adding exhaust flame dampeners, glare shields, and special landing lights.
There were no FW-190A5/U13 was fitted to FW-190A5/U2 standards until 1944.
Explain how SKG10 could be testing /U13 a/c if they were not converted (???) to that configuration until 1944.
You are confusing the varients Milo. It is easy to do.
Crumpp