A GMCnetter disagrees with these documents.....

The locked up splines and too much mainline pressure theories etc. suggested in the article are garbage, basically. I suspect the modification regarding
loose fit of the main thurst bearing in the engine might be effective, but there is no transmission problem per se, not from design, from wear or any
other point of view.

Significant restriction of the cooler lines is bad news, the modification suggested to the converter fill circuit may work if its the oil flowing IN and not OUT of the converter. The 300 PSI figure is balderdash, no factory assembled GM transmission hits that kind of pressure, think 220 is the maximum in the GMC at any point. This is still less than 1/3 the pressure a manual transmission clutch pressure plate exerts as thrust on a crank.

My view after examination of the whole deal is clearly its an engine assembly problem and has pretty much nothing to do with the transmission. The THM 400 does exert under some circumstances a force loading the crank a bit, but its a very insignificant load and only for very short duration, and quite a bit less than stepping on the clutch of a 4 speed manual equipped engine exerts. The modification to restrict the oil flow will might lower converter pressures somewhat but would not be highly effective.

Brent Covey (10-2-02)