Crown for GMT 16750

[pigred054]

Hi, recently I brought my GMT 16750 to RSC requesting for servicing. RSC quoted me a price for servicing and replacement of the rotor, and offered me a free replacement of crown (bigger crown they said) and crystal. Then RSC called again few days later saying that the 4 hands must be replaced (also free) otherwise they could no longer proceed the servicing. I refused to replace the hands and took back the watch.

I believe the current crown I have is 5.3mm, just wonder what the biggest crown I can fit to 16750? the 5.3mm crown is not easy to operate and thinking to change a bigger crown in other watch repair shop.

BTW, could anyone tell me my 16750 having a correct era dial for 870xxxx serial? It doesn't look like a mark 4 dial I searched on internet but more like a later 16700 dial.
However, there are lots of similar dial I found on chrono24 and other sites around the same period (1984~86)... so confusing