I have dealt with the SX50 since it first came out and since it uses "registers" to program it is not fun to deal with. You do not have any switches on the card for LS or GS, it is in programming where you tell it what type of trunk.
The trunks are punched down every other pair starting at the top of the block. You would ony use 8 pairs on an 8 port card. If you have a manual you should have some programming forms. Trunks are programmed in the 5XX forms so your 65 trunk would be under 565.
