They are not the only place that has crossover steering..one thing with them is they do not supply a flat top knuckle.Which you will need seeing you have a '77 and most likely does not have a flat top on the passenger side..
These were called down style knuckles on the older years.
A place I know
www.blackbirdscustomtrucks.com Sells the whole setup with a passenger knuckle and options to get the driverside too.
They also will talk to you and get correct measurements for the length of crossover tube.
Crossover page
I would save and do the crossover. It is way better in the long run for durability, and lasting.
No bind what so ever and easy to install hydro assist later on to help move the big tires.
Had a buddy with the stock side used for a 10 suspension lift and a raised arm and superlift draglink.. wore out fast..
and cost almost as much to replace parts
Just an idea to go with..
Look around on the net for prices..