D2 4u side tank model counterweight question

I have a d2 4u with a side fuel tank. I am installing a new hahn seat in it. But the lower seat cushion is too high. There are 4-5 large 4x4 inch steel bars that interlock together and appear to be counter weights. The seat has to sit on top of them and therefore it is too high.
My question is..... Are those counterweights actually a caterpillar option? Or did the previous owner just put them in to aid in traction.
Let me know if anyone has any info on this. My only option if i want to install the seat is to remove them.
Thanks
andy

Never heard of that before. You say they're under the seat?

never seen items in the parts book or attachments guide. interlocking = lots of work.

Got any pictures?

I would say they are some kinfd of traction aid as tipping is a perennial complaint re D2s, especially early ones fitted with blades - hence the attraction with fitting a winch out the back😊