We sell them neutral balance, 5.9 magnum or 360 LA. They have been available for several years.
The problem is now most early engines have a million miles on them and there are tons of cheap late model ones with 100K on them. I bought 2 $800 Durangos last week, 120K and 132K. I also dont understand how its easier to use OBD I with any trans compared to OBD II, we do it all the time. You should also check out the fuel injected tanks we sell, much better idea than drilling holes in your tank. BTW I have boxes of OBD I harnesses if they are getting scarce.