What is this on my rear axle?

Does anyone know what these mounts are that have been welded to my rear axle? In the picture i circled in red 3 mounts i dont know what they do. The blue lines are the mounts the bypass shocks bolt to. Bypass shocks bolt to the roll cage. I bought the truck used so i dont know previous setup. It currently has stock leaf springs with 4" bracket to drop the leafs lower. Its a 98 tacoma 5 lug

 

Truck or truck the axle came from had a 3 link rear previously

 

I thought it could be for a 3 link suspension but all 4 link setups look different and i have no mounts welded on fram or cab anywhere.

 

Axle prob came from anothe truck then

 

So what kind of link suspension would have the links facing rearward? Maybe a truck that was slammed low. Its just weird looking. I would like to eventually install link suspension and was trying to find out if i could even buy the kit previously used on the axle,but it could have been custom fabricated

 

Oh wow I didn't notice that those were all rear facing... Maybe it was a cantilever set up ? ...but then it would not need the center point ?