If the dish feed is old-
cband version that uses a servo (blue box on the back with 3 wires) then the best way is to completely replace the feed.
The channels (odd/even) are controlled by that servo, and you will have to change channels manually on the old receiver to get both horiz and vert. transponders.
Which is a hassle.
The
bsc621 is well regarded in this forum.
I have recently replaced the positioner system on my BUD with a
vbox and I am on the verge of replacing the feed with the BSC621.
Larry