Its a grey grease that is very thick and from what the guy at speedometer shop told me the grease doesn't leak it burns up due to the high temps in the cluster
My 97' had the same problem with the gas gauge there is a fix what you do is find a local speedometer repair shop and they can inject the grease in to the motor itself for about 50$
My tuned 5.3 in my new truck would walk all over my old tuned 5.7 vortec es the 350 did have more low end grunt but once you get it above 3k it falls on its face compared to the 5.3
I bought this kit to convert the SBC 1 piece transmission in my 97 to a LS style transmission which in my opinion are far superior to the early 4L60E's
http://www.gmperformanceparts.com/Parts/Transmissions/Adapters/Transmission-adapter-kit.jsp
The spider I had was on its way out and insurance came and picked up the truck on Monday sorry try this
http://www.amazon.com/Delphi-FJ10566-Fuel-Injector/dp/B000TYLIFS/ref=pd_sim_auto_4 its the updated version and its less prone to problems like the early ones