FAILURE OF TRANSMISSION AT HIGHWAY SPEED; FLUID SPILLED ONTO ROAD CAUGHT FIRE UNDER ENGINE COMPARTMENT; COMPLAINED TO DEALER ABOUT HARD SHIFTING FROM 1-2; AND VAN SURGING FORWARD WHEN COMING TO A STOP; DEALER CLAIMED NO PROBLEM PERFORMED B51 SERVICE UPDATE PRIOR TO PROBLEM; OVERDRIVE SLIPS IN AND OUT ON INCLINE; REQUIRES REMANUFACTURED TRANSMISSION. *AK