IIRC you might have to make them. What year is your Riv (put in sig?)
I would not bother making urethane shock mounts or strut mounts, would instead just use the Monroe or Gabriel ones. The OE ones are IMHO a bit too soft for their own good, but I think the stiffer ones for the Bonneville might fit. Abbadon might know for sure.
There was a write up somewhere on casting your own urethane motor mounts.
On the later Rivs some of the suspension bushings are not, by design. really replaceable. But the components they are in (front control arms for instance) come with them in already.
Had my car up on a rack at the dealership last week. I was surprised to see that my front and rear control arm bushings were fine. I am thinking that with 215000 miles they'd be clapped out by now, but they are not.
I replaced all the engine and transmission mounts at about 120,000 miles. Replacing the front motor mount, in hindsight, was not necessary at that time. Replacing the rear tranny mount absolutely was, it was torn. The other mounts were checked.
I looked at the mounts last week. My transmission mount could stand replacement some time this year or next, It is not ripped yet but it's checked. It'd be great, I think, to get a lo-durometer (like, OE stiffness or a smidgen stiffer) urethane fill in that mount, it's be as cushy as OE but I would not have to mess with it for the next 100000+ miles. The front mount did not look bad although it has some surface checking. I wonder if that could have been prevented with a preservative like 303 Aerospace Protectant?
As far as shocks and struts go, I'd use Gabriels or KYBs on the fronts, OE on the rear. A number of people really like the Monroes on the rear and I have no reason to argue - I just thought Monroes were too soft on the *front* for my taste and I've always been able to get OE rears at reasonable price (RockAuto sells them with mounts attached, I think they are NOS they're getting from somewhere, and the mounts, well that's like $60 right there). Thing I like about the Gabriels on the front is the damping changes depending on how fast and how far the piston moves. SO they soak up the little bumps like pavement seams almost unnoticed, and they give great control for the kind of driving I do (higway speeds on rural smooth secondary roads) getting rid of the bobbing that Rivs with OE struts tend to do when you go over quick undulatins at speed. I would still have those struts on teh car but the casings corroded and started seeping. So I did not use the warranty I changed brands. The KYBs I have now are great as well but are a bit stiffer over those pavement dividers, they communicate more fo those little bumps, but not annoying.
By the way if you get Monroe sturts, you might be sure also to replace the springs - they have 'position sensitive valving' and won't work right unless your ride height is at factory spec on all 4 corners.