Same problem I had with the last transmission?

My Truck:  79' Chevy Silverado K-10, 350/th350/203

My problem:  After lending my truck to a "friend" All forward gears were toast. Reverse worked fine. I admit it took me a long time to replace the th350 with a new one , mostly because i know how heavy and combersum the np203 TC is. anyway i bought a used th350 from a salvage yard with a 90 day garentee(90 days start when i return with core) and the owner said he knew  personally  that it was a good running unit. and it looked the part. inside the fluid was mostly drained. but the small amount  nt that was there looked pink (prob new pink) no metal bits or piece in the pan maybe a little grey fine dust in the corners. but looked good for the most part  So half way into the project I discovered the two top holes on the output housing were striped out (the ones that bolt through the adapter plate and into the trans) 2of4, I decided that my best option at that point was to, replace the top two with same type/size/thread bolt just 1/2" longer and backed them up with nuts. installed new filter and the only other problem. i found was  my truck had the aluminum flywheel starter cover with the steel rods that connect the trans to the motor mounts. and this trans. didnt have the bolt holes to acomidate that. (i drilled holes in it to put it on) The guy that i had helping me for some reason didn't fill the tork converter before hand. (which by the way was the T/C from the trans. that just came out) I wouldn't say it was drained 100% i just put it upside down on top of a five gallon bucket till we needed it. I will say at this point that the fluid in my original trans was the worst ive ever seen. (color/Smell/metal) back to my story....  We ended up at 11qt fluid in total. i got reverse gear at about 8qt.It also has Natural. but never got any forward gears. it does shift and hold in each position normally but no gear. Dipstick reads full, truck is warmed up, as is my temper. and i woke up this morning and couldn't remember doing the modulator.  as it turns out he put the old modulator on the new trans, but not the short rubber hose cause he couldnt find it. So i still haven't ran the truck complete yet but i don't think that going to give me 1st 2nd and 3rd gear is it?
It just seems odd that this trans has same reverse only problem my trans had. don't it?. I haven't called the salvage yard yet, im sure he will make it right. I just wish i could charge him labor $$ for this  but? Any thoughts? any help? any vodka? any Bullets?
 

Well live and learn. As a rule of thumb for me I would never replace a transmission with out replacing the torque converter to.I am not a transmission expert but since that is the only "same part" in your swap then you leave yourself with a hole in your install.Another problem you now have is if there was any crud in the converter it is now in the tranny too. You'll probably be pulling it out again.In my opinion I lean to the converter but this is not gauranteed. Anyone else with opinion? Good luck and keep us posted.  

id say its the modulator. its sets the line pressuers  

Wouldn't it still go in gear.The modulators I have replaced were because the trans wasn't shifting properly or it was leaking thru the vacuum line but would at least go in gear. Just a question.