A couple of sources.
I believe I saw a black one on the LMC part site.
Truckline Sport Grip has an 18 inch leather lace cover but only in black for now. They are no longer producing the tan or gray one. Trying to find a retailer that may have an old tan or gray one in stock.
No problem finding a cover in smaller sizes but for us with vintage trucks that doesn't solve the problem.
Hope this helps.