I was under the GT the other day and see my lower control arms (rear) have lost their seal so for now I'm leaving them alone for now.
Ford wants about $1,800 for newbies each side. This your problem?
I found that both the rear lower control arm outer boots and toe link outer boots crack in cold weather. I had stored 2 sets of lower control arms in my unheated area of shop and the boots cracked from the cold. The set I had inside was fine. Anyways, I located a suitable replacement on ebay from a seller in Bulgaria back in 2018. Ordered them and received - no issues. I see he still sells them. It does take a while for shipment.
https://www.ebay.com/itm/2-X-HQ-Rub...Rubber-Boot-/223440044400?hash=item3406108170
We need Need to haVe someone make a replacement seal kit as this is common.