Here's a pic of the elbow and dipstick installed on a ZF. As I recall, the dipstick was made from a 5/16" cotter pin and a flat disc (washer?) with a 5/16" hole. The cotter pin was silver soldered to the flat disc, and one "leg" of the cotter pin was completely removed. The other "leg" was shortened and marked.
The elbow appeared to be blue anodized, which might suggest that it was an AN fitting.
This doesn't answer the fill level questions, but....
John