Did this job last year on my '90 2.6 M103 engine. Pretty simple. Only a little to remove for access. I did not replace the insulators on mine (at 100+K miles) and have not had a problem. The older mechanical style injectors do wear and will leak after a time. Mine had evidently been doing so after engine shut down. When I replaced all 6, under two of them (4&5) there was a wetness in the manifold after removing the injectors. Cured the slight, stumbling, rich-flooded re-start I was experiencing after an hour to a day or so of standing.