I have (2) Mendota fireplace inserts. Model D40 Seabrook and Model DXV 42. They both have the same parts list. I keep having to replace the thermocouple and thermopile. I have propane. They only last a year or so then need to be replaced. I know that there is a HD thermocouple but that doesn't seem to make any difference. They are expensive also. Is there any aftermarket replacement for the following items and model numbers.

05-07-00061 Thermopile
05-07-00084 Thermocouple (HD for propane)