Mystery part on rear driveline

[junkyardjohn]

ATF IS NOT SUPPOSED TO BE USED IN THESE OLD NP205s. THEY ARE GEAR DRIVEN. THE REASON MINE WERE FILLED WITH ATF WHEN I DRAINED THEM IS BECAUSE THERE ARE TWO OIL SEALS.. BACK TO BACK IN THE ADAPTER HOUSING BETWEEN THE AUTO-MATIC TRANNY (EITHER A T-350 OR A T-400) & THE NP205 TO KEEP THE ATF IN THE TRANNY FROM MIGRATING INTO THE TRANSFER CASE. WHEN THESE SEALS FAIL.. THE ATF GOES INTO THE T/C & PUSHES THE GEAR OIL (80 OR 90 WT.) OUT THE OVERFLOW AND FILLS THE T/C WITH ATF OUT OF YOUR TRANNY. ONCE IT IS REPLACED WITH ALL ATF IT WILL QUIT. IT LEAKS OUT THE OVERFLOW ONLY WHEN THE TRANSFER CASE IS SPINNING SO YOU DON'T NOTICE A BIG PUDDLE IN YOUR DRIVEWAY. I LEARNED THIS MYSELF THE HARD WAY. NEVER UNDER ANY CIRCUMSTANCES FILL A 205 WITH ANYTHING BUT GEAR OIL. THE NEWER MODEL CHAIN DRIVEN NEW PROSESS T/Cs LIKE THE 203 OR 208 TAKE REGULAR OLD ATF, BUT IT DOESN'T HAVE THE LUBRICATING PROPERTYS TO PROTECT A GEAR DRIVEN T/C LIKE A 205 UNDER ANY KIND OF LOAD OR EXTREEME HEAT. DO SOME RESEARCH ON IT. I LEARNED ABOUT THIS MYSELF BACK BEFORE WE HAD COMPUTERS (IT WOULD BE EASY TODAY)& READ SEVERAL BOOKS & SERVICE MANUALS ON THESE TRANSFER CASES,(ALL THE WORLDS KNOWLEDGE IS CONTAINED IN PRINT ) BECAUSE I DRAINED TWO DIFFERENT ONES WITHIN A COUPLE OF YEARS & BOTH WERE FULL OF ATF & I'M NOT MUCH OF A BELIEVER IN COINCIDENCES. I WAS QUITE PERPLEXED UNTIL I LEARNED THIS. WITH A LITTLE ANNUAL MATENANCE THESE OLD CAST IRON NP205s WILL LAST FOREVER, BUT YOU HAVE TO HAVE THE PROPER LUBE. WERE TALKING ABOUT 1960s TECHNOLOGY HERE. IGNORE EM... & THEY WILL FAIL. JOHN