Did you try a Google search ?
They probably not list shock for BJ70 since that truck was not sold in USA and there only few of them was sold in Canada (+/-660).
Well, the market is so small they probably don’t waste time to build those shocks for this specific model.
What I’m suggesting to you: take a look at the other shock builder and look for cross reference with other model. For example, BJ70 rear shock = FJ62 rear shock.
On other hand, you can buy it oversea !
Good luck.
PS : there plenty of shock supplier (Monroe, KYB, Bilstien, OME, Gabriel, OEM,...) … don’t get stuck on Koni product.