I thought this question might go good in this forum, in case anyone else has the same idea. We're getting ready to fit the engine in, and I'm wanting to bolt the mounts in. My dad is saying we should weld them in for a stronger fit. I can see the risk of a nut/bolt vibrating loose. But I can also see a weld cracking and the mount just "sliding" around on the crossmember. Eventually I would like to buy a matched set of mounts/headers for neatness and the sheer sake of being matched. What would you reccomend? If we weld the mounts, how hard would it be to eventually remove them?

My mounts are welded in. The people that originally did the swap did it, so I just left it this way. It wouldn't be hard to get them out, just need to do alittle grinding.

Bolt them. You can use a good quality grade 8 bolt, have a hole in your mount or plate and weld the bolt to the plate and also have an anti rotation feature built into your mount. Use a lock washer or lock nut and it won't move.

Here is what we did, bolted the mounts in using lock-tight and lock washers then we tact welded the four corners of the L&L mounts. It is the best of both worlds.

so even on my 86 just bolting them in with some lock tight and locking nuts would work good? or what is a better way?>

This is what we're going to do:

I have the L&L mounts now..we tried bolting them into the crossmember in the available holes. But, it just doesn't work, I guess the 351 is too wide from mount to mount. We have the mounts assembled and mounted to the motor, and we're going to lower it into the bay. When we get it setting where we want, we're going to mark the spot, then drill a hole through the middle of the lower plate. Insert a #8 bolt, then tack weld the four corners. Then if we ever need to take them out, it wouldn't be a huge ordeal.

Bolting alone should be fine as long as your have quality hardware and are torqued down enough. I imagine the more torque you start pumping out of the engine, the more you'll want to beef up the mounting.