Hello and welcome to JustAnswer!
The price to do the conversions will depend on the labor rate of the shop doing the work, the kit that is used and whether or not the shop supplies the parts.
There are several kits available. For the either of the trucks you'd be looking at about $1,000-1,200 for the kit if you purchased it yourself and then took it to the shop doing the work. If you allowed the shop to order the parts for you then you'd end up paying markup on the part which would probably be a couple hundred dollars on a high priced item like this.
Labor to install the kits will run in the area of $800 or so depending on the shop's hourly rate.
Are there additional costs such as a storage tank?