Early yoke welding

I've always taken cast iron to 500F, welded with Ni-rod & wrapped in Kaowool or other good insulation material which can be quickly packed around it to prevent rapid cooling after bumping the heat up when finishing the weld. Rapid cooling is very prone to cracking. Just my $.02 and what has work for me, but never have cottoned to welding cast iron if new part is available..... really don't trust it over the long term.

What filler would you use with a MIG welder?
ER70S3

Firstly you MUST identify parent material ie if yoke malleable cast can be readily welded by brazing preheat 500f whole yoke do not overheat you will change the metallurgical structure and cause brittleness (a long story)no post heat reqd let it cool down out of any draught. Countersink and plug with mild steel rod or bolt if holes go through a little added strength something for brass filler rod to stick to use a suitable flux rather than flux coated rod for better adhesion DO NOT melt yoke or plug when brazing get every part clean as possible do not grind when prepping try and keep heat to a minimum to reduce heat affected zone (problem area) if you can’t braise weld ok I would enlist someone who can cast iron welding with correct consumables can salvage lots of parts destined for scrap bin. Not as hard as it sounds hope this helps.(stay away from stainless axles another thread perhaps)Boilermaker/welding inspector

Preheat can be higher around 900f will help sweat the metals openings pores to hot and brass will ball up to low won’t flow

being hollow I'm quite certain they are an investment casting in steel, certainly not cast iron.
They are easily bent and I have straightened lots. the holes wont cause a problem but could
easily be welded up with no special gear.