Hi New on NG.
Found it!!!!!!!!!!!!
You are right, I was so mad at not being able to remember where I had seen that limitation, that I forgot to check in my -200 manuals!
It's not in the limitations, but in the Supplementary Normal Procedures, Automatic flight, Non precision approach:
Except as noted, do not use the VOR/LOC AFDS mode when conducting VOR approaches if any of the following conditions exist:
No co-located DME transmitter available at the VOR station to be used or when the DME is invalid for any other reason.
The VOR/DME station elevation is more than 5000 feet MSL.
Then they add that these problems exist only if you are gonna
overfly the station during the approach.
Problem (and headache) solved!
Happy landing with the mask on in La Paz!
LEM