what year and model car is this in? what engine is the D15B replacing? is this a ZC L3 transmission, with intermediate shaft and equal length axles?
typically, the 88-91 L3 cable clutch transmission will bolt right up to any of the 88 and up SOHC D-series engines - just need to make sure that the clutch matches the transmission - the ZC transmission which uses the intermediate shaft and equal length axles doesn't work with the D15B, as there is no place to bolt the intermediate shaft to the block