First read this thread about what engines will fit right into a luv:
http://forums.luvtruck.com/viewtopic.php?p=97181&highlight=#97181
Then you can check here:
http://car-part.com/
There is no charge for buyers...(it's a lot safer than buying from some clown you don't know on ebay), it's partnered with every known Auto Recycler Association in The USA and Canada, and it's been around since 1998.
Just pick the year (such as 84-86), and the model(such as Isuzu Impulse), and the part (engine), pick the area(mine is Pacific and Northwest - but you can use whatever is best for where you live), put in your zip code, and search...and you will find quite a few.
You can sort them all by price, by quality rating (A-C, A being the best), and they also give any info available about the vehicle, the mileage racked up on the vehicle that the part came from, the year of the vehicle it came from, the part's condition, the yard's location and how far it is from you, the yard's phone number, the price (if available), etc.
This site charges a hefty fee (around $300.00 per month) for Auto Recycler businesses to sign up and join as a member, screens their applicants carefully, won't take any yard that isn't a member of any known Auto Recycler Association, and updates their part inventory several times a day...so it should find you anything you'll need for you without any problems.
Most yards listed with them will ship it to you as cheap as possible too, if it's feasible.
Hope this helps ya.