I have a 95 blazer with a bad trans and was wondering if a 98 jimmy trns would fit in it?

 

The 98 trans will be a two piece case (removable bell housing) while your 95 will have a single piece case. It will bolt up, but you won't have a cover (dust shield) for the lower portion.

The next issue is that you have to determine if you have a PWM TCC solenoid. You have to pull your transmission and look at the pump cover (behind the torque converter). It should have PWM in raised letters on it. If it does not, you cannot use any of the PWM TCC versions of the 4L60E which were used from mid-95 on.

And finally, you'll want to get a transmission from a vehicle with the same drivetrain configuration as your truck (ie. 2wd to 2wd or 4wd to 4wd).