1996 k3500 reg cab long bed cab swap w/ 1998 cab....some issues???

[babyajay]

Sorry I am new to the forum and could use some insight if possible. I have a 1996 K3500 work truck, 5.7L with no a/c. My cab was heavily rotted so i ended up changing the whole cab. i used a 1998 k1500 cab with a/c. The k1500 has the 5.7L as well. When i took off the cab from my k3500 i simply disconeccted the main harness from the cab and renconnected to the new cab. The truck starts and and even shifts gears, however, my tachometer does not work, my brake lights do not work, fuel and oil pressure guages dont work and my gear selector does not work? I am assuming that there are compatability issues between the years. Anybody ever do a cab swap or have any insight?