what 4 speed auto transmissions can i use? 46rh etc

Hey guys
Is there anyone in the mopar world who has a good name for building transmissions. I am not after a big dollar 1000hp trans but would like someone who knows mopar transmissions and there weaknesses and strengths well.

I have a a518 that has a shudder that comes in and out almost like it's timed.the shudder is very noticeable when driving but is also there while stationary with the revs up around 2000rpm. Because it's there in park that discounts the tail shaft and tyres etc. I had the engine balanced and it did not shudder on the engine dyno. My engine balance weight is on the flex plate and I have had the converter balanced twice. Still no luck. I have run the engine briefly with no exhaust to see if it's harmonics but still no good.
Could the fact that my transmission still has the lock up valve body in it but has a 2800 non lock up stall converter be causing me issues? Maybe the valve body needs mods to suit a non lock up converter.
Anyone know a place that specialises in valve body's I can call and ask.