At the end of the part number of an individual part is the suffix "G" this should denote that it is OEM spec, i.e. original fitment or equivalent. If it does not have this then it "may" not be as good quality. ( this is a bit of a minefield).
As i said have a look on LRDirect if you have the kit part number ( STC4096L ??) or give them a call, the people there seem very knowledgable.
I cannot remember the exact kit I used from LR Direct unfortunately. But individual part numbers were OEM equivalent.
Also, depending on how old the engine is, has it had the newer drive pulley fitted with the flange? Old kit had the flange on the tensioner pulley.
Cheers