3.9 block swap

98 dakota---needs a short block--found a low milage from a 91----figured to change the heads out--found the 98 uses the stretch head bolts and the 91 has standard LA headbolts--and there are different threads to those bolts----looks like i can put on the new heads on with the old headbolts-----any other quirks going to show up with the timing cover/waterpump? yeah i know the damper and pullys are different---thanks bob

you need to use the newer bolts, one of the long ones is a different length, they should all be the same thread. The 91 probably ain't got no where to put the crank sensor.

the stretch bolts are a bigger thread diameter---probably metric---dont think there is a crank sensor on the 98 motor---if there is then this idea is over----will need to get the right block----bob

98s use a crank position sensor. it's what tells the engine when to fire the spark. all the MPFI magnum engines do (I don't know about the earlier TBI motors).

---will have to get the right block after all---thanks guys---bob

I have use the newer bolts in the older blocks many times, they are the same threads, I just checked a 1989 block with 2000 MY head bolts. Mabey your bolts got mixed up with something else or some where along the way the newer block got a stripped bolt and someone drilled and tapped it for different bolts