transducer compatability

[salty_dog_68]

i am in the process of purchasing a pre-owned sailboat. the knot meter and depth instruments have long since become inoperable. my question is...if i can not find an exact replacement can i use the transducer from the old stowe instruments with a different mfg. of instrument? should they be compatible? do the trx of different mfg. use different "languages" to transmit data to the instrument ? how long should a bronze t/h trx last?

thanks,

salty