I picked up these NOS tange forks and was wondering the year or years they were produced. They feel heavy and by researching believe they are mild steel. They are stamped TANGE 9K MADE IN JAPAN. What bikes came with these besides Mongoose/ what years would they serve as replacements or an aftermarket fork? Would they work on a Hutch? Didn't see Tange around in the mid to late 80s as a kid. Any help would be appreciated.

Yeah I don't think are cro-mo - that is the TX500 which has square holes in the drop outs.

9k is November 1979 for Tange Date Codes.

That is the TX-1200 leading axle fork. They also came in straight axle.