99 Ram 1500 Knocking in first 3 gears

I have a 99 Ram 1500 5.2 liter 5 speed manual that knocks loud when accelerating in 1st, 2nd and 3rd gear but when i shift to 4th it stops. All my fluids are clean and full. There were no prior issues or noises the knock just stARted while i was driving home on the freeway. Im stuck because its a holiday weekend and most shops are closed or their techs are out of town. Knock sensor, EGR time delay switch, wire set, choke thermostat....these are some of the suggestions I've gotten but this knock sounds like its coming from the gear box and with out any shops open I just wanted to see if anyones had the same issue. What was the problem and solution. ANYONE!!!!!:1zhelp::1zhelp: