1998 Chevy Venture rod bearing

Engine Mechanical problem
1998 Chevy Venture 6 cyl Two Wheel Drive Automatic

I found out last year, after finding coolant in my engine, that the intake mnaifold gasket had failed, evidently a common occurance on this make and model of car. Also, the oil was tested and showed signs of aluminum?
I took a chance and had the gasket and pushrods replaced in the upper part of the engine, and then drove it for several months-- about $1200 for the job.
While on the highway, the engine started to knock and lose power. I stopped and had it towed to a auto shop.
A mechanic told me, from listening to it, that as rod bearing had gone out.
My question is, whether or not it is possible to fix the rod bearing from the bottom of the car, without having to have the engine removed. I hate to "throw " away the previous repair work that was done, and I don't really have the cash to have a rebuilt engine put it.
Wes