From the book Dodge Viper by Daniel F. Carney:
Looking back, it seems astonishing that Team Viper was also building a radical new engine from a nearly clean sheet of paper, to a deadline pace. Ruling out the truck engine meant the team members had to build what they wanted themselves.
Said Francois Castaing "It was already April 1989. If we wanted the car to be ready by January 1992, we needed to really get going. But the timing for the truck engine was a year later. It also became obvious, when we looked at it more thoroughly, the weight of the iron engine was too high and the power we would get from it wouldn't be sporty enough." Francois was in charge of truck engineering at the time.
Said Roy Sjoberg , Team Viper's new executive engineer,"We rapidly ascertained, the truck guys and myself, that where we wanted a 6,200-rpm redline, the truck guys didn't really care to go over 4,200 rpm. They were interested in low-end torque, not horsepower at high-rpm levels where we were. They were not concerned about weight. Truckies don't like aluminum blocks. They're not as forgiving, and truck people like to have things that are pretty bulletproof.
"Not a lot could be learned from our truck V-10 development. Both engines were V-10s, but one was aluminum and one was iron; ours was sequential-fire individual-injected, and the truck's was group-injected, so it ended up having air pumps and things. We only needed EGR to meet the initial emission requirements, as well as a catalyst. The truckers had to put some other things on it. We ended up with the same dimension pushrod and that was it. But even there, we used a higher-grade material because of our power and rpm requirements."
In the end, there wasn't a single shared part with the Ram V-10 that was being built elsewhere within Chrysler.
So they only share displacement and the pushrods have the same dimensions.