The struts are generic and can be ordered on Amazon, eBay, or anywhere really. It is not necessary, and is a waste, to worry about getting them from an OEM source. These are the ones I recently bought for my 1998 Sportster 1800:
https://www.amazon.com/Lift-Support...vpo4qqCJUy0mpKLymLc-PsZKAv2tQ9r0Aitb_tGe9BAyY
They are 10lbs stronger than my OEM ones because I wanted the lid to pop open better, but the extra force didn't do anything anyway. The part number for my original ones would have been sl34-80 instead of sl34-90.