I built a 4r100 tried using red eagle power packs had nothing but bad luck unless u make them shift so hard feels like the trannies going to fall out seems to be the only way to use those. I ended up machining pressure plates and using stock frictions with an extra one in intermediate,forward,direct and od. I use transgo hd shift kits and a few sonnax parts on top of those with a few of my own mods. Trans is behind early 99 with a 38r and hybrid injectors do believe 238cc. This was the first big power trams I did and had a few issues at first with the aftermarket clutches I talked about but has been good now for a year and half. Also this truck is plowed with in the winter with a 9'2 v blade with extensions. Converter I use has a billet cover and 6.0 pump which lowers the stall have had great feed back on these even in stock apps. If you take you time and so research u can build a solid unit for way less than 5k especially If if your not going for big power JMO