Are these interchangeable?

Yeah, thats what I thought; The reverse inner lever was changed to accommodate a different cheapazz interlock. Thx for the pic. So My mistake;your box will not take any cover,lol, cuz it sure won't work with the 80's style interlock.
The threads on the studs have to be pretty nice to hold their torque. If/when the nuts work loose, the shifter loses it's neutral gate and then shifting becomes difficult. The nuts work loose cuz the external levers have "wallered-out"(thx RRR) slots. This has to be addressed,now. And if the levers are wallered out then the studs have rounded corners. There is no easy fix for this cuz both of those items are hardened. What I do is with the cover on the bench drop the levers on correctly oriented, and load up the gaps with red loc-tite, I install the special fine-thread nuts,torque them up (IIRC 15 ftlbs), And flip the cover over, nut-side down.The trick now is to not let the loc-tite find its way into the space between the levers and the cover. That stuff wicks so, my solution is to come back every 10 to 15 minutes and shift them a bunch of times, to make sure it still shifts. Finding out it doesn't,after the tranny is up, is very frustrating.
Don't forget O/D boxes get the 3-4 lever installed upside down! All levers have an in-side and an out-side.If you don't recall what goes where, mock it up before the loc-tite goes in......lol